Show reactions in the pinned messages list

[bxdxnn]

Content

Support showing/adding reactions for messages in the pinned messages list

Motivation and context

They weren't shown before, I'm not sure if that was intentional though.

Screenshots / GIFs

Tests

• Test that you can see the reactions for messages in the pinned messages list's timeline
• Test that you can add reactions to messages in the pinned messages list's timeline

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.

[bmarty]

A comment for now: reactions are not shown on pinned event list in purpose, because they may not be accurate. Element X iOS does not show them either.

The problem we observed in the past is related to the reaction aggregation, which is not always working correctly. Reaction are events in the timeline, and for old events (pinned or not, but pinned events could get more late reactions than not pinned ones), that can get reactions from the time they were sent to now, it can render inaccurate reactions list.

I have been told that some improvement has been done SDK side regarding this, so it's maybe better now.