feature(room preview): Add option to forget room, improve the room preview screen for banned rooms.

Some internal refactoring was done too:
- Remove RoomInfo.isPublic to only use JoinRule.
- Also take into account restricted access rooms for previews.

features/roomlist/impl/src/main/kotlin/io/element/android/features/roomlist/impl/model/RoomListRoomSummaryProvider.kt

@@ -123,6 +123,7 @@ internal fun anInviteSender(
     userId = userId,
     displayName = displayName,
     avatarData = avatarData,
+    membershipChangeReason = null,
 )
 
 internal fun aRoomListRoomSummary(