Consolidate the way JWK sets are loaded

[sberyozkin]

At the moment the JWT sets are dealt with in two different places. First mp.jwt.publickey.location is checked if it points to a JWK set resource in KeyLocationResolver. Next if an internal followMpJwt11Rules is set then it is assumed that instead of mp.jwt.publickey.location jwksUri was set and the keys are loaded not in the resolver but in the parser. So we have two ways to point to JWKs, only one of them is used in smallrye-jwt while the jwksUri path is used via a followMpJwt11Rules diversion from Thorntail.

This really needs to change and followMpJwt11Rules needs to go as it is confusing (and will become more so when we move to newer versions of MP JWT). Instead KeyLocationResolver should keep all the code for loading the keys, for example, it can check if the location starts from https etc.
JWTAuthContextInfo jwksUri should also be renamed to publicKeyLocation or similar, otherwise at the moment, if is actually used to load PEM keys as well, it is initialized with mp.jwt.publickey.location which adds the extra confusion.

[sberyozkin]

Good opportunity to fix it now given that we plan to release 2.0.0