[Ban AI] Add Vue scaffholding for Group and Admin

To accelerate development of the Ban AI, we need to create a common structure between admin and group settings as most of the settings will be similar. This issue is to track the work to introduce the new Vue apps in Group and Admin behind a disabled feature flag: ai_powered_settings_vue. This issue will:

1. Add the Feature flag ai_powered_settings_vue
2. Add the index.js file to initiate ai settings applications
3. Add the common structure for our Vue components
4. Add the ruby helpers structure to allow a centralize way to initiate data from the serve and pass it to the client side
5. Have the conditional rendering in the haml to only show the Vue apps if the feature flag is enabled.

This issue will not:

1. Have a working settings page
2. Have the toggle for the settings
3. Implement API actions