Added ability to use platform provider of translations on macOS.

Telegram/SourceFiles/lang/translate_provider.cpp

@@ -7,6 +7,8 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 */
 #include "lang/translate_provider.h"
 
+#include "core/application.h"
+#include "core/core_settings.h"
 #include "data/data_msg_id.h"
 #include "data/data_peer.h"
 #include "data/data_session.h"
@@ -18,6 +20,10 @@ namespace Ui {
 
 std::unique_ptr<TranslateProvider> CreateTranslateProvider(
 		not_null<Main::Session*> session) {
+	if (Core::App().settings().usePlatformTranslation()
+		&& Platform::IsTranslateProviderAvailable()) {
+		return Platform::CreateTranslateProvider();
+	}
 	return CreateMTProtoTranslateProvider(session);
 }