Use the same UI as Android when tapping a link to a private room. (#3044)

* Use the same UI as Android when tapping a link to a private room.

* Fix preview of knocking.

* Fix snapshots.

ElementX/Sources/Screens/JoinRoomScreen/View/JoinRoomScreen.swift

@@ -51,10 +51,11 @@ struct JoinRoomScreen: View {
                     .foregroundStyle(.compound.textPrimary)
                     .multilineTextAlignment(.center)
                 
-                if let alias = context.viewState.roomDetails?.canonicalAlias {
-                    Text(alias)
+                if let subtitle = context.viewState.subtitle {
+                    Text(subtitle)
                         .font(.compound.bodyMD)
                         .foregroundStyle(.compound.textSecondary)
+                        .multilineTextAlignment(.center)
                 }
                 
                 if let memberCount = context.viewState.roomDetails?.memberCount {
@@ -168,6 +169,7 @@ struct JoinRoomScreen_Previews: PreviewProvider, TestablePreview {
         
         return JoinRoomScreenViewModel(roomID: "1",
                                        via: [],
+                                       allowKnocking: true,
                                        clientProxy: clientProxy,
                                        mediaProvider: MockMediaProvider(),
                                        userIndicatorController: ServiceLocator.shared.userIndicatorController)