Rework on messages view top bars

[bmarty]

Content

Extract code for the messages view top bar to reduce file size. Create dedicated Preview for the top bar and reduce the number of Preview for MessagesView, for a faster rendering in the IDE.

Motivation and context

Smaller file size
Better performance on rendering previews of MessagesView.
Complement for #5374

Screenshots / GIFs

The recorded one should be OK, and the code coverage should not decrease.

Tests

• No expected behavior / UI change, it's just some rework.

Tested devices

• Physical
• Emulator
• OS version(s):

Checklist

• Changes have been tested on an Android device or Android emulator with API 24
• UI change has been tested on both light and dark themes
• Accessibility has been taken into account. See https://github.com/element-hq/element-x-android/blob/develop/CONTRIBUTING.md#accessibility
• Pull request is based on the develop branch
• Pull request title will be used in the release note, it clearly define what will change for the user
• Pull request includes screenshots or videos if containing UI changes
• You've made a self review of your PR

[github-actions]

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[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[codecov]

Codecov Report

❌ Patch coverage is 96.96970% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 80.37%. Comparing base (cc38651) to head (321c5f6).
⚠️ Report is 24 commits behind head on develop.

Files with missing lines	Patch %	Lines
...atures/messages/impl/topbars/MessagesViewTopBar.kt	96.82%	0 Missing and 2 partials ⚠️
...oid/features/messages/impl/topbars/ThreadTopBar.kt	96.87%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #5401      +/-   ##
===========================================
- Coverage    80.37%   80.37%   -0.01%     
===========================================
  Files         2282     2284       +2     
  Lines        63069    63066       -3     
  Branches      7887     7887              
===========================================
- Hits         50692    50689       -3     
  Misses        9464     9464              
  Partials      2913     2913              

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