Add NimbusJwtDecoder#withIssuerLocation

[jzheaux]

Related #8885, #9904 (comment)

It would be nice to be able to provide an issuer location to NimbusJwtDecoder instead of a JWK Set URI.

It would allow the issuer discovery to share the same RestOperations/WebClient as the decode method does. Since the JWK Set is cached, this will save a call to the authorization server and also allow the RestOperations and WebClient used for issuer discovery to be configured.

This should be added for both NimbusJwtDecoder and NimbusReactiveJwtDecoder.

[jgrandja]

@jzheaux Please see this comment as a potential alternative to this issue. Any feedback would be greatly appreciated.