This commit aims to simplify the way developers can access company related information in the web client. Before this commit, in components, they had to import the `userService` hook and do something like `this.company = userService("company")` in the setup. In services, they had to explicitly declare the dependency on the company service. In other functions (like helpers), it was a bit painful: the function had to take an env in arguments, which wasn't ideal.

This commit makes it easier to access the company information. The company service has been removed. Instead, we use the existing `user` object which can be imported directly from anywhere. The `user` object was chosen because the company information is all related to the currently logged-in user.

For clarity, the company information has been renamed: 

user.allowedCompanies: The list of companies that the user is allowed to log in to. Note that any of the other companies in the following keys will always be in this list.
user.defaultCompany: The default company to log in to, if the cookies are empty.
user.activeCompanies: The list of the companies that the user is currently logged in to
user.activeCompany: The main company that the user is currently logged in to. This is the company displayed in the main navigation bar in the web client. 


Note that, something similar has already been done for the `user` service, the `cookie` service, the `router` service, and the `rpc` service.

This commit also allows the `user` object to take ownership of the company related information in the session. The problem before this commit was that there were 2 sources of truth for company related information : the company service and the `session_info`. The information is sent from the server to the client within the page (in `session_info`). Then the company service was built using this information. This means that the developer could access the information in 2 different ways. Now, the `user` object takes the full ownership of these company related keys by removing them from the session after reading them. Note that, something similar is already done for the user related information and for the currencies (see currency.js).

Part-of task-id 3621046
Part-of task-id 4250356
Part-of task-id 2224776

Since [1], this flow is broken:

1. Install website_helpdesk => You have a "Help" menu with an helpdesk team as url (/helpdesk/customer-care-1) which is created

2. Check: if you publish or unpublish your team, that menu is visible or invisible as a public user.

3. Create a new menu for your website, with that same URL (/helpdesk/customer-care-1)

4. Check: that menu is always invisible as a public user. Even if you remove the first menu.

Multiple mistakes were made with [1]:

- The website menu visibility override code was added twice in two different files.

- The override advertises that this is for "always showing the helpdesk team menus even if they are unpublished" but it is actually meant to be the exact opposite of that.

- The implementation is based on the menu that are linked to the helpdesk teams, not on their URL **.

- The implementation actually bypass the normal visibility computation for all menu URL that start with "/helpdesk", meaning a custom page "/helpdesk-hello" from the user is just broken, so as existing controllers not linked to an helpdesk team (such as /helpdesk/rating).

**: actually this could mean that this feature is just not meant to be given the current state of the codebase: creating a menu with a team URL should just make it so it is forcefully linked to that team or should be prevented if it cannot (?).

[1]: https://github.com/odoo/enterprise/commit/a888fb57ebd2458bc8479e187088cb2e96b811fa

opw-3931376

Forward-Port-Of: odoo/enterprise#76797
Forward-Port-Of: odoo/enterprise#63105

An error occurs when the system tries to access single values from multiple records at [1].

Link [1]: https://github.com/odoo/enterprise/blob/2e1af04e36fcbdcd11e3a7e2994673b2c4a5cf85/social_youtube/models/res_config_settings.py#L19

Traceback On Sentry:

```
ValueError: Expected singleton: res.config.settings(105, 106)
  File "odoo/http.py", line 2366, in __call__
    response = request._serve_db()
  File "odoo/http.py", line 1894, in _serve_db
    return self._transactioning(
  File "odoo/http.py", line 1957, in _transactioning
    return service_model.retrying(func, env=self.env)
  File "odoo/service/model.py", line 137, in retrying
    result = func()
  File "odoo/http.py", line 1924, in _serve_ir_http
    response = self.dispatcher.dispatch(rule.endpoint, args)
  File "odoo/http.py", line 2171, in dispatch
    result = self.request.registry['ir.http']._dispatch(endpoint)
  File "odoo/addons/base/models/ir_http.py", line 329, in _dispatch
    result = endpoint(**request.params)
  File "odoo/http.py", line 727, in route_wrapper
    result = endpoint(self, *args, **params_ok)
  File "addons/web/controllers/dataset.py", line 35, in call_kw
    return call_kw(request.env[model], method, args, kwargs)
  File "odoo/api.py", line 517, in call_kw
    result = getattr(recs, name)(*args, **kwargs)
  File "odoo/models.py", line 6090, in search_read
    return records._read_format(fnames=fields, **read_kwargs)
  File "odoo/models.py", line 4032, in _read_format
    vals[name] = convert(record[name], record, use_display_name)
  File "odoo/models.py", line 6999, in __getitem__
    return self._fields[key].__get__(self)
  File "odoo/fields.py", line 1291, in __get__
    self.compute_value(recs)
  File "odoo/fields.py", line 1473, in compute_value
    records._compute_field_value(self)
  File "odoo/models.py", line 5238, in _compute_field_value
    fields.determine(field.compute, self)
  File "odoo/fields.py", line 110, in determine
    return needle(*args)
  File "home/odoo/src/enterprise/18.0/social_youtube/models/res_config_settings.py", line 19, in _compute_youtube_oauth_client_id
    if self.env.user.has_group('social.group_social_manager') and self.youtube_use_own_account:
  File "odoo/fields.py", line 1232, in __get__
    record.ensure_one()
  File "odoo/models.py", line 6212, in ensure_one
    raise ValueError("Expected singleton: %s" % self)

```

To resolve this issue, Use an iteration(for loop) to iterate records one by one.

Sentry-6200420369

Forward-Port-Of: odoo/enterprise#76588

Before Commit:
-----------------------------
- When a user makes a sign request for himself he can refuse the request by
clicking on the refusal button.
- Currently a user can edit the extension in the template name. It does not
affect the original file but still does not provide a good user experience.
- Rpc calls were made when you insert a sign item, move a sign item, delete the
sign item.

After Commit:
-----------------------
- The user will not be able to refuse a sign request he made for himself
- Removed . form Setting labels
- Changed the Sign Items pop-up button on from Validated to Save
- Improved the Kanban View
- Improved the Selection sign item pop-up by adding a custom Many2Many field
- Now the extension of a file is read only and a user cannot edit it.
- A new sign status indicator is added to reduce the number of rpc calls.
- Now only the rpc call is made when a user manually saves it, changes the view
or clicks on a sign item.

task-3911221

Forward-Port-Of: odoo/enterprise#64194