[Feature Request] Exposes publicly override of AadIssuerValidator factory taking a delegate

[jmprieur]

Is your feature request related to a problem? Please describe.
We want to be able to get an AadIssuerValidator from an authority and also a cached BaseConfigurationManager

Describe the solution you'd like
AadIssuerValidator GetAadIssuerValidator(string aadAuthority, HttpClient httpClient, Func<string, BaseConfigurationManager> configurationManagerProvider) exists but is internal. The ask is to make it public.