Add alert to encrypted rooms with visible history (Android).

[kaylendog]

Content

• Adds a dismissable alert that is displayed whenever the user opens a room with history_visibility != joined. When cleared, this is recorded in the app's data store.
• When opening a room with history_visibility = joined, this flag is cleared.`

Motivation and context

This is part of ongoing work to implement production-ready encrypted room history.

Issue: element-hq/element-meta#2875

Screenshots / GIFs

Tests

1. Create a new private (encrypted) room. Since Element X defaults to invited history visibility, the new banner should be visible immediately upon opening the room.
2. Dismiss the banner, then re-open the room. It should not be visible.

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]

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

• 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.

[kaylendog]

I'm not sure if this is the correct naming scheme to use?