Render media captions formatting in the media viewer

[bxdxnn]

Content

Motivation and context

Fixes #6506

Screenshots / GIFs

Tests

• Open a media that has Markdown in the caption

Tested devices

• Physical
• Emulator
• OS version(s):

Checklist

• This PR was made with the help of AI:
  • Yes. In this case, please request a review by Copilot.
  • No.
• 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 defines 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]

Thank you for your contribution! Here are a few things to check in the PR to ensure it's reviewed as quickly as possible:

• If your pull request adds a feature or modifies the UI, this should have an equivalent pull request in the Element X iOS repo unless it only affects an Android-only behaviour or is behind a disabled feature flag, since we need parity in both clients to consider a feature done. It will also need to be approved by our product and design teams before being merged, so it's usually a good idea to discuss the changes in a Github issue first and then start working on them once the approach has been validated.
• Your branch should be based on origin/develop, at least when it was created.
• The title of the PR will be used for release notes, so it needs to describe the change visible to the user.
• The test pass locally running ./gradlew test.
• The code quality check suite pass locally running ./gradlew runQualityChecks.
• If you modified anything related to the UI, including previews, you'll have to run the Record screenshots GH action in your forked repo: that will generate compatible new screenshots. However, given Github Actions limitations, it will prevent the CI from running temporarily, until you upload a new commit after that one. To do so, just pull the latest changes and push an empty commit.

[jmartinesp]

Thanks for the contribution. I think the PR needs some more work, if you were using an AI agent I think it got some things wrong about the current setup 😅 .

[bxdxnn]

Yes, sorry, this PR was vibecoded as there were some weird bugs that I wasn't able to solve because of media viewer flickering, but as I've fixed the media viewer this PR started to work automatically. I'll resolve the code smell manually.

[codecov]

Codecov Report

❌ Patch coverage is 91.83673% with 8 lines in your changes missing coverage. Please review.
✅ Project coverage is 81.23%. Comparing base (a7711b7) to head (eeef6e4).
⚠️ Report is 10 commits behind head on develop.

Files with missing lines	Patch %	Lines
...es/mediaviewer/impl/datasource/EventItemFactory.kt	16.66%	0 Missing and 5 partials ⚠️
...braries/mediaviewer/impl/viewer/MediaViewerView.kt	85.00%	1 Missing and 2 partials ⚠️

Additional details and impacted files

@@           Coverage Diff            @@
##           develop    #6729   +/-   ##
========================================
  Coverage    81.23%   81.23%           
========================================
  Files         2628     2628           
  Lines        73334    73424   +90     
  Branches      9484     9493    +9     
========================================
+ Hits         59572    59649   +77     
- Misses       10269    10277    +8     
- Partials      3493     3498    +5     

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[jmartinesp]

I'm uploading a few quick fixes that should unblock this.