feat: Add support for dark mode in dashboard (#7460)

- Add config for TailwindCSS
- Enable HMR
- Add a config in LocalStorage for Dark Mode

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

app/javascript/dashboard/constants/localStorage.js

@@ -2,4 +2,5 @@ export const LOCAL_STORAGE_KEYS = {
   DISMISSED_UPDATES: 'dismissedUpdates',
   WIDGET_BUILDER: 'widgetBubble_',
   DRAFT_MESSAGES: 'draftMessages',
+  COLOR_SCHEME: 'color_scheme',
 };