Define a java module for JWTPublicKeyExtractor

* Component to extract the json web key from the jwt token.
* JWTPublicKeyExtractor
* extractKey(oAuthToken Base64EncodedJWT) : JWK // Token from server
* We assume the JWT contains a claim named "res_pub_key"
* The format and the location of this information might be dependent on the target identity provider.
* We prefer the IdP keeping this out of the access_token or refresh_token
* IdP can put this in the oAuthToken
* an identity provider might decide to put it accessToken because there is nothing else send to the client.
* So the public key extractor will be configured to work with the target idp