use isDM from the SDK to determine if a spaceRoom, a joinedRoom or a notificationItem are from a dm room.

NSE/Sources/NotificationItemProxy/NotificationItemProxyProtocol.swift

@@ -35,6 +35,8 @@ protocol NotificationItemProxyProtocol {
     var isRoomDirect: Bool { get }
     
     var isRoomPrivate: Bool { get }
+    
+    var isDM: Bool { get }
 
     var isNoisy: Bool { get }
 
@@ -42,9 +44,3 @@ protocol NotificationItemProxyProtocol {
     
     var threadRootEventID: String? { get }
 }
-
-extension NotificationItemProxyProtocol {
-    var isDM: Bool {
-        isRoomDirect && roomJoinedMembers <= 2
-    }
-}