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.

ElementX/Sources/Screens/RoomScreen/RoomScreenViewModel.swift

@@ -101,6 +101,9 @@ class RoomScreenViewModel: RoomScreenViewModelType, RoomScreenViewModelProtocol
                 Task { await resolveIdentityPinningViolation(userID) }
             case .resolveVerificationViolation(let userID):
                 Task { await resolveIdentityVerificationViolation(userID) }
+            case .dismissHistoryVisibleAlert:
+                appSettings.acknowledgedHistoryVisibleRooms.insert(roomProxy.id)
+                state.footerDetails = nil
             }
         case .acceptKnock(let eventID):
             Task { await acceptKnock(eventID: eventID) }
@@ -342,6 +345,16 @@ class RoomScreenViewModel: RoomScreenViewModelType, RoomScreenViewModelProtocol
             state.canDeclineKnocks = powerLevels.canOwnUserKick()
             state.canBan = powerLevels.canOwnUserBan()
         }
+        
+        // Whever the user opens a room with joined history visibility, we clear the dismiss flag to ensure that the banner is displayed again if the history is made visible in the future.
+        if roomInfo.historyVisibility == RoomHistoryVisibility.joined {
+            appSettings.acknowledgedHistoryVisibleRooms.remove(roomInfo.id)
+            state.footerDetails = nil
+        }
+        // Whenever the user opens an encrypted room with non-join history visbility, we show them a warning banner if they have not already dismissed it.
+        else if roomInfo.isEncrypted, !appSettings.acknowledgedHistoryVisibleRooms.contains(roomInfo.id) {
+            state.footerDetails = .historyVisible(learnMoreURL: appSettings.historyVisibleDetailsURL)
+        }
     }
     
     private func setupPinnedEventsTimelineItemProviderIfNeeded() {