Reduce API of JoinedRoom, caller must use the Timeline API from liveTimeline instead

[bmarty]

Content

Reduce API of JoinedRoom, caller must use the Timeline API from liveTimeline instead

Motivation and context

Removes lots of boilerplate code
Improve test coverage.

Screenshots / GIFs

Tests

• No particular thing to check

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

Attention: Patch coverage is 79.03226% with 26 lines in your changes missing coverage. Please review.

Project coverage is 80.29%. Comparing base (11ac725) to head (be70b58).
Report is 9 commits behind head on develop.

Files with missing lines	Patch %	Lines
...oid/libraries/matrix/test/timeline/FakeTimeline.kt	79.64%	22 Missing and 1 partial ⚠️
...features/poll/impl/actions/DefaultEndPollAction.kt	0.00%	1 Missing ⚠️
...poll/impl/actions/DefaultSendPollResponseAction.kt	0.00%	1 Missing ⚠️
...ment/android/features/share/impl/SharePresenter.kt	0.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #4731      +/-   ##
===========================================
+ Coverage    80.13%   80.29%   +0.15%     
===========================================
  Files         2129     2129              
  Lines        56449    56334     -115     
  Branches      7055     7056       +1     
===========================================
- Hits         45236    45232       -4     
+ Misses        8795     8685     -110     
+ Partials      2418     2417       -1     

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