Right panel: view third party invite info without clearing history (#11934)

* add View3pidInvite to actions enum, replace uses

* extract out action handler

* push card instead, test

* comment

src/dispatcher/actions.ts

@@ -376,4 +376,9 @@ export enum Action {
      * Fired when the room loaded.
      */
     RoomLoaded = "room_loaded",
+
+    /**
+     * Opens right panel with 3pid invite information
+     */
+    View3pidInvite = "view_3pid_invite",
 }