Fix a possible crash in Go to Message on macOS.

Fixes #26273.

This crash happens with a very deep stack trace that is caused by
destroying shared media layer on Go to Message click, which starts
destroying Media::ListWidget, which destroys Ui::PopupMenu, which is
a window, so when it destructs it triggers a sync repaint of the main
window (by a system event), which tries to render the new messages slice,
which starts a photo download, which calls an item repaint in Data::Session,
and the semi-destroyed Media::ListWidget is still subscribed to the
item repaint requests and tries to repaint and crashes there.

The fix is to destroy all session-related subscriptions before the PopupMenu.

Telegram/SourceFiles/info/media/info_media_list_widget.h

@@ -295,7 +295,6 @@ private:
 	bool _wasSelectedText = false; // was some text selected in current drag action
 
 	const std::unique_ptr<DateBadge> _dateBadge;
-	base::flat_map<not_null<Main::Session*>, rpl::lifetime> _trackedSessions;
 
 	base::unique_qptr<Ui::PopupMenu> _contextMenu;
 	rpl::event_stream<> _checkForHide;
@@ -305,6 +304,8 @@ private:
 	QPoint _trippleClickPoint;
 	crl::time _trippleClickStartTime = 0;
 
+	base::flat_map<not_null<Main::Session*>, rpl::lifetime> _trackedSessions;
+
 };
 
 } // namespace Media