chore: Add action to set dark mode from the react-native-widget (#7167)

Co-authored-by: Pranav Raj S <pranav@chatwoot.com>

app/javascript/widget/store/modules/specs/appConfig/mutations.spec.js

@@ -24,4 +24,12 @@ describe('#mutations', () => {
       expect(state.widgetColor).toEqual('#00bcd4');
     });
   });
+
+  describe('#SET_COLOR_SCHEME', () => {
+    it('sets dark mode properly', () => {
+      const state = { darkMode: 'light' };
+      mutations.SET_COLOR_SCHEME(state, 'dark');
+      expect(state.darkMode).toEqual('dark');
+    });
+  });
 });