update proposed.timeline API and update theia timeline view implementation

[ndoschek]

What it does

Resolves GH-16623

• [vscode] update proposed.timeline API
  • update proposed API to 1.106.1
• update theia timeline view implementation
  • update theia/timeline implementation to updated proposed api
    • make use of hoverService for new tooltip
    • add icon to timeline item
  • simplify css styling and reuse existing tree css classes
  • add localization to missing user-facing text in timeline widget

How to test

• Open the Timeline view in the Theia Explorer and open a source file that has git commit history (e.g. the root package.json)
• Verify that the tooltips work as expected and show details of the timeline item
• Verify that the timeline item shows the respective icon and has proper styling
• Verify that the user-facing strings are now localized (i.e. the load more button, refresh button, empty view info)

Follow-ups

Breaking changes

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

Attribution

Contributed on behalf of STMicroelectronics

Review checklist

• As an author, I have thoroughly tested my changes and carefully followed the review guidelines
• User-facing text is internationalized using the nls service (for details, please see the Internationalization/Localization section in the Coding Guidelines)

Reminder for reviewers

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