fix: manage AI bindings separately per connection

[sdirix]

What it does

Moves all AI backend bindings into ConnectionContainerModules. Therefore these are now scoped per connection (i.e. frontend) instead of globally for all connections.

The global bindings lead to a lot of interference when multiple connections were open. In fact AI streaming did only work for the latest connection.

Related to #14143

How to test

• Open multiple tabs/windows of Theia and verify that Theia AI works in all of them.
• Verify that AI features are connection scoped, e.g. use workspace preferences for AI models, open two different workspaces at the same time and observe that the expected models show up in the corresponding windows

Follow-ups

Related to #14143 this prepares the code base to simplify / streamline a lot of the delegation mechanics.

Breaking changes

• This PR introduces breaking changes and requires careful review. If yes, the breaking changes section in the changelog has been updated.

Attribution

Review checklist

• As an author, I have thoroughly tested my changes and carefully followed the review guidelines

Reminder for reviewers

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