[Feature]: Support of custom domain and custom cert by Azure SignalR module

[Y-Sindo]

Description of the new feature

1. Verification that the SignalR Service still exists Implemented by Get-AzSignalR
2. Verification that the Custom Certificate is configured with the expected Certificate
3. Verification that the Custom domain is configured with the expected Custom domain
4. Verification that the CORS allowed origins contains only the URLs that we expect
   We can get the CORS with $(get-azsignalr -ResourceGroupName $resourceGroupName -Name $resourceName).Cors

Proposed implementation details (optional)

No response

[microsoft-github-policy-service]

Thanks for the feedback! We are routing this to the appropriate team for follow-up. cc @sffamily, @chenkennt.