Websites - Move the ResourceGroup filtering for GetCertificates to the server

[nking-1]

Description

This is a small optimization for reading web app certificates from the ARM cache. The resource group filtering is moved to the server side instead of the client side. This will greatly reduce the size of the HTTP response for subscriptions with a large number of certificates.

#9392

Checklist

• I have read the Submitting Changes section of CONTRIBUTING.md
• The title of the PR is clear and informative
• The appropriate change log has been updated
• The PR does not introduce breaking changes
• If applicable, the changes made in the PR have proper test coverage
• For public API changes to cmdlets:
  • the changes have gone through a cmdlet design review (Microsoft internal partners only)
  • the cmdlet markdown files were generated using the platyPS module

[markcowl]

This requires a changelog entry. Also, tests are failing, please correct.

[panchagnula]

@markcowl is there a way to get this merged for this current sprint? thank you.