feat: Working VoIP calling implementation (Flutter + Android)

Working video and audio calls, as well as android integration

lib/models/call_state.dart

@@ -0,0 +1,28 @@
+enum CallState {
+  Idle,
+  IncomingReceived,
+  PushIncomingReceived,
+  OutgoingInit,
+  OutgoingProgress,
+  OutgoingRinging,
+  OutgoingEarlyMedia,
+  Connected,
+  StreamsRunning,
+  Pausing,
+  Paused,
+  Resuming,
+  Referred,
+  Error,
+  End,
+  PausedByRemote,
+  UpdatedByRemote,
+  IncomingEarlyMedia,
+  Updating,
+  Released,
+  EarlyUpdatedByRemote,
+  EarlyUpdating;
+
+  static CallState fromOrdinal(int ordinal) {
+    return values[ordinal];
+  }
+}