Allow POP extensibility API on all requests

[bgavrilMS]

Fixes https://github.com/AzureAD/microsoft-authentication-library-for-dotnet/issues/4757

Changes proposed in this request

Testing

Performance impact

Documentation

• [ ] All relevant documentation is updated.

[trwalke]

When the associated task says "everywhere", Im assuming you mean available to all Acquire Token methods on the Confidential client right?