Add a banner to encrypted rooms with visible history. (#4851)

* Add a banner to encrypted rooms with visible history. (#4738)

* feat: Add history visible alert.

- 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.

Issue: element-hq/element-meta#2875

* tests: Add unit tests for history sharing in `RoomScreenFooterView`.

* feat: Rename flag to `hasSeenHistoryVisibleBannerRooms`, document.

* refactor: Merge enum variants, use function for banner description.

* feat: Use `AppSettings.historyVisibleDetailsURL` over hard-coded value.

* tests: Correct potential race condition with deferred assertion.

* chore: Use Localazy translation string over project-defined.

* fix: Final tweaks and review comments.

* chore: Checkout `Enterprise` submodule.

* tests: Final fixes.

* fix: Condition banner visibility on feature flag state.

* fix: Prioritise identity violations over history visibility banner.

* tests: Add snapshots for history visible banner.

* tests: Use deferred failure timeout for improved test power.

* chore: Tweaks to spelling, simplify state logic.

* fix: Remove "g".

* fix: Show banner for shared/world-readable rooms, not invited.

* refactor: Use `else-if` instead of `if`.

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