Steps to reproduce:
-------------------
1. Go to Appointments and configure an Appointment Type (e.g., Dental care).
2. Remove the admin(apt manager) user (e.g., "Mitchell Admin") from the Users(staff_user_ids) for that type.
3. Click on the "Appointments" stat button
4. Click the "New" button to create a new appointment record.
5. Try to save the record.

Issue:
------
A Validation Error is raised:
```
"Mitchell Admin" cannot be used for "Dental Care"
```
Cause:
-------
After this 5928fda, we support inverse capacity for user appointments. This method
[_inverse_resource_ids_or_capacity](https://github.com/odoo/enterprise/blob/397de08c3b772228819416d2f5bb80ccda34b795/appointment/models/calendar_event.py#L355-L360) triggers the method [_check_user_or_resource_match_appointment_type](https://github.com/odoo/enterprise/blob/397de08c3b772228819416d2f5bb80ccda34b795/appointment/models/appointment_booking_line.py#L45-L46)
and it will check, appointment_user_id (admin) is not part of the appointment type’s staff_user_ids,
causing a false incompatibility.

**NOTE**:
If we create an appointment by clicking on a slot on the gantt view, it won't cause an issue
as it explicitly updates `user_id` based on `default_partner_ids`. https://github.com/odoo/enterprise/blob/f40e24e67a1664a13acdd01578d8269d084ee421/appointment/models/calendar_event.py#L66-L69

solution:
-----------
Use `has_access` to ensure the current user is allowed to create.

opw-5273175

Forward-Port-Of: odoo/enterprise#101437