change: stricter private timeline media visibility

ElementX/Sources/Services/Room/RoomInfoProxy.swift

@@ -49,6 +49,17 @@ struct RoomInfoProxy: BaseRoomInfoProxyProtocol {
     
     var isDirect: Bool { roomInfo.isDirect }
     var isPublic: Bool { roomInfo.isPublic }
+    
+    // A room might be non public but also not private given the fact that the join rule might be missing or unsupported.
+    var isPrivate: Bool {
+        switch roomInfo.joinRule {
+        case .invite, .knock, .restricted, .knockRestricted:
+            true
+        default:
+            false
+        }
+    }
+    
     var isSpace: Bool { roomInfo.isSpace }
     var isTombstoned: Bool { roomInfo.isTombstoned }
     var isFavourite: Bool { roomInfo.isFavourite }