CfSingleSignOnProcessor should set jwk-set-uri

[xyloman]

In order for spring boot resource servers to automatically build a JwtDecoder, the property spring.security.oauth2.resourceserver.jwt.jwk-set-uri should be set CfSingleSignOnProcessor so that OAuth2ResourceServerJwtConfiguration.java builds the JwtDecoder bean.

[xyloman]

Otherwise with out this configuration an application has to set the jwk-set-uri property themselves with the information that comes from the service binding:

spring:
  security:
    oauth2:
      resourceserver:
        jwt:
          jwk-set-uri: ${identity.auth_domain}/token_keys
          jwk-set-uri: ${vcap.services.identity.credentials.auth_domain}/token_keys

[dyroberts]

java-cfenv-boot-pivotal-sso module is presently only supporting spring-security oauth2 client properties.
This request implies supporting resource server as well, which is a good idea.
However, most recent docs suggest setting only the ...resourceserver.jwt.issuer-uri property.
https://docs.spring.io/spring-security/site/docs/5.3.2.RELEASE/reference/html5/#oauth2resourceserver-jwt-minimalconfiguration
I'll have to take a look at this a little further.
I could also consider a contribution if you want to submit a PR @xyloman!