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

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

app/javascript/packs/sdk.js

@@ -146,6 +146,12 @@ const runSDK = ({ baseUrl, websiteToken }) => {
       IFrameHelper.sendMessage('set-locale', { locale: localeToBeUsed });
     },
 
+    setColorScheme(darkMode = 'light') {
+      IFrameHelper.sendMessage('set-color-scheme', {
+        darkMode: getDarkMode(darkMode),
+      });
+    },
+
     reset() {
       if (window.$chatwoot.isOpen) {
         IFrameHelper.events.toggleBubble();