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/assets/scss/widgets/_modal.scss

@@ -34,7 +34,6 @@
 .modal-container {
   @include normal-shadow;
 
-  background-color: $color-white;
   border-radius: $space-smaller;
   max-height: 100%;
   overflow: auto;