Add OAuth to API calls

In order to limit access to certain features (such as POST access), OAuth verification will be added to the stack. For current features, we just need to verify token against the Accounts API service, but in the future we plan to use OAuth scopes to allow access to limited resources (such as the cache access to manage API data).

Quarkus has stated that it has its own mechanisms for handling OAuth, and it should be investigated to see if it meets our needs.