These changes unify four different approaches to JWT creation, moving the core of the AccessTokenView to a general-purpose JwtBuilder class. This utility class defaults to using the system's JWT configuration, but it will allow overriding of the signing key and audience claim to support those clients which still require this. Part of ECOM-4566.

ECOM-4653

Retrieving the URL from settings rather than an OAuth client that might not exist.

ECOM-4729

ECOM-4441