Properly dispose tab/title-based resources on tab close

[martin-fleck-at]

What it does

The complete tabs model is only disposed and re-created whenever we we need to initialize it (no groups are available), we detect a broken state (we cannot find a tab that should be present) or when the overall tab groups have changed. This re-creation disposes the listeners we have on the current tab bars. However, in this group of listeners we also have some listeners that are only related to a particular tab/widget/title and they do not get properly disposed when a single tab is closed. The goal of this PR is to fix this.

Fixes #14203

How to test

• Use the Chrome Developer Tools to make Memory snapshots and observe the behavior of closing and opening tabs over time.
• Some resources are cleaned but you can observe that after closing all tabs after having several open, we have memory X and after opening a single tab again the memory is less than X because we triggered the re-creation of the tabs model.
• In the new version the memory size should naturally follow the number of open tabs.

Follow-ups

Review checklist

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

Reminder for reviewers

• As a reviewer, I agree to behave in accordance with the review guidelines

[martin-fleck-at]

@dfriederich FYI

[msujew]

Thanks, looks good to me 👍