feat: Pin invited rooms

Invitations should always be on top of the
room list. This makes it an optional parameter now which defaults to
true.

lib/src/client.dart

@@ -160,6 +160,7 @@ class Client extends MatrixApi {
     this.importantStateEvents,
     this.roomPreviewLastEvents,
     this.pinUnreadRooms = false,
+    this.pinInvitedRooms = true,
     this.sendMessageTimeoutSeconds = 60,
     this.requestHistoryOnLimitedTimeline = false,
     this.supportedLoginTypes,
@@ -1576,6 +1577,9 @@ sort order of ${prevState.sortOrder}. This should never happen...''');
   /// If `true` then unread rooms are pinned at the top of the room list.
   bool pinUnreadRooms;
 
+  /// If `true` then unread rooms are pinned at the top of the room list.
+  bool pinInvitedRooms;
+
   /// The compare function how the rooms should be sorted internally. By default
   /// rooms are sorted by timestamp of the last m.room.message event or the last
   /// event if there is no known message.

lib/src/room.dart

@@ -545,7 +545,9 @@ class Room {
   }
 
   /// Returns true if this room has a m.favourite tag.
-  bool get isFavourite => tags[TagType.favourite] != null;
+  bool get isFavourite =>
+      tags[TagType.favourite] != null ||
+      (client.pinInvitedRooms && membership == Membership.invite);
 
   /// Sets the m.favourite tag for this room.
   Future<void> setFavourite(bool favourite) =>