feat(flutter): 重构播放页并增加语言切换

test/mine/mine_preview_layout_test.dart

@@ -60,11 +60,12 @@ void main() {
       Key('mine-creator-center'),
       Key('mine-notices'),
       Key('mine-settings'),
+      Key('mine-language'),
       Key('mine-help'),
     ]) {
       expect(find.byKey(key), findsOneWidget);
     }
-    expect(find.byKey(const Key('mine-language')), findsNothing);
+    expect(find.byKey(const Key('mine-language')), findsOneWidget);
     expect(find.byKey(const Key('mine-library-tab-0')), findsNothing);
     expect(find.byKey(const Key('mine-library-tab-1')), findsNothing);
     expect(find.byKey(const Key('mine-library-tab-2')), findsNothing);