Removed Main::Session forward declaration from data_types.

Telegram/SourceFiles/api/api_chat_invite.h

@@ -12,6 +12,10 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 class UserData;
 class ChannelData;
 
+namespace Main {
+class Session;
+} // namespace Main
+
 namespace Window {
 class SessionController;
 } // namespace Window

Telegram/SourceFiles/api/api_sending.h

@@ -7,6 +7,10 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 */
 #pragma once
 
+namespace Main {
+class Session;
+} // namespace Main
+
 class History;
 class PhotoData;
 class DocumentData;