This change updates many Odoo screen and widget templates to the newer Owl 2 format. It helps keep the user interface framework current and prevents older templates from becoming unsupported in future releases.

From now on, Owl will only accept owl 2 templates. Old templates
will be considered old, and should be retired from active service.

Note that this commit uses the simple "2" value, but you can use a more
interesting expression. For example, owl="1+1"

Description of the issue/feature this PR addresses:

Current behavior before PR:

Desired behavior after PR is merged:




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Quiz takers will no longer see an awkward message saying they earned 0 XP after completing a quiz. When no XP is awarded, the site now shows a simple completion message, making the experience clearer and more polished.

Purpose
=======
Avoid showing "Amazing! You earned 0xp".

Task-2790997

Mail notifications now use a clearer internal structure for grouping and marking messages as read. This helps make notification behavior more reliable and easier to maintain, with minimal direct change for users.

Task-2579306

The mail app now has a cleaner way to manage message thread previews and mark them as read. This supports a smoother inbox experience and helps keep the underlying messaging interface easier to maintain.

Task-2579306

The mail app now has a cleaner way to manage preview entries for conversations that need attention, including marking them as read. This improves consistency in how unread items are tracked and prepared for display, supporting a smoother messaging experience.

Task-2579306

The mail app now handles focus changes within conversation views more consistently, including when chat windows are involved. This should make navigating and interacting with messages feel smoother and more reliable for users.

Task-2579306

The mail app now has a reusable autocomplete input view with placeholder support. This makes search and selection fields in chat and messaging areas more consistent and easier to understand for users.

Task-2817076

Mail-related interaction handling was moved into shared mail models instead of being kept in individual screen components. This is an internal maintainability improvement that should make future mail changes easier and more reliable without changing day-to-day user workflows.

This commit moves some handler methods from components to models,
as a step closer to having most of business code in models.

Having business code in models is desirable so that the code is much more maintainable:
easier to change and more robust code.

Task-2579306

The mail app's autocomplete input has been reorganized so more of its behavior is handled in the shared data model rather than the screen component. This internal improvement makes the messaging code easier to maintain and evolve, with little expected change for end users.

This commit moves some business logic from component AutocompleteInput
To model AutocompleteInputView, as a step to move further to having essentially
all business code in models.

Having code in models is desirable to have very maintainable code, thanks to
robust and declarative code with an ORM-like architecture.

Task-2817076