chore: Custom Roles to manage permissions [ UI ] (#9865)

In admin settings, this Pr will add the UI for managing custom roles (
ref: https://github.com/chatwoot/chatwoot/pull/9995 ). It also handles
the routing logic changes to accommodate fine-tuned permissions.

---------

Co-authored-by: Pranav <pranavrajs@gmail.com>
Co-authored-by: Sivin Varghese <64252451+iamsivin@users.noreply.github.com>
Co-authored-by: iamsivin <iamsivin@gmail.com>
Co-authored-by: Muhsin Keloth <muhsinkeramam@gmail.com>

app/javascript/dashboard/featureFlags.js

@@ -31,4 +31,5 @@ export const FEATURE_FLAGS = {
   IP_LOOKUP: 'ip_lookup',
   LINEAR: 'linear_integration',
   CAPTAIN: 'captain_integration',
+  CUSTOM_ROLES: 'custom_roles',
 };