Can request call offer

lib/helpers/calls_helper.dart

@@ -34,4 +34,8 @@ class CallsHelper {
                 ))
             .toList()
             .cast<CallMember>());
+
+  /// Request an offer to access another peer's stream
+  static Future<void> requestOffer(int callID, int peerID) async =>
+      await ws("calls/request_offer", {"callID": callID, "peerID": peerID});
 }