Re-evaluate JwtExtension and maybe create new Extension for using a real Context setup

[chrisrohr]

JwtExtension was created to assist in setting up a user for the resource tests, however, it is not really setting up the whole JWT token, it is just mocking things.

With DeployableSystemResourceTest, we figured out how to configure the ResourceExtension to have the filters and JWT token processing. Need to investigate extracting this into a new Extension and update other tests to use it.