add RequiresClient capability

Author: toger5

src/interfaces/Capabilities.ts

@@ -20,7 +20,8 @@ export enum MatrixCapabilities {
     Screenshots = "m.capability.screenshot",
     StickerSending = "m.sticker",
     AlwaysOnScreen = "m.always_on_screen",
-
+    // Ask Element to not give the option to move the widget into a seperate tab.
+    RequiresClient = "io.element.requires_client",
     /**
      * @deprecated It is not recommended to rely on this existing - it can be removed without notice.
      */