[Fix] Resolves Domain Dialog Issues

[RichardAnderson]

This pull request introduces improvements to the domain management workflow, focusing on optimizing how available domains are fetched and refreshed from DNS providers. The main changes include adding caching for domain retrieval, introducing a backend refresh endpoint, and updating the frontend to support domain list refreshes and improved user experience.

Backend enhancements:

• Added a new action class GetAvailableDomains that retrieves available domains from a DNS provider, caches the results, and filters out domains already added, improving efficiency and reducing unnecessary API calls.
• Modified DomainController to use the GetAvailableDomains action for fetching available domains, and added a new refreshDomains endpoint to force a refresh and bypass the cache. [1] [2]

Frontend improvements:

• Updated the add-domain.tsx component to support refreshing the domain list via the new backend endpoint, including a refresh button with loading state and improved form reset logic when opening the dialog. [1] [2] [3] [4]
• Added the RefreshCw icon for the refresh button in the domain selection UI.

Unit Tests:

• Updates existing unit tests to ensure that a cache is used for /available
• Creates new unit tests to ensure that cache is not used on /refresh

Resolves #1042