fix(api): issue2551384. Verify REST authorization earlier To reduce the ability of bad actors to spam (DOS) the REST endpoint with bad data and generate logs meant for debugging, modify the flow in client.py's REST handler to verify authorization earlier. If the anonymous user is allowed to use REST, this won't make a difference for a DOS attempt. The templates don't enable REST for the anonymous user by default. Most admins don't change this. The validation order for REST requests has been changed. CORS identfied an handled User authorization to use REST (return 403 on failure) REST request validated (Origin header valid etc.) (return 400 for bad request) Incorrectly formatted CORS preflight requests (e.g. missing Origin header) that are not recogized as a CORS request can now return HTTP status 403 as well as status 400 (when anonymous is allowed access). Note all CORS preflights are sent without authentication so appear as anonymous requests. The tests were updated to compensate, but it is not obvious to me from specs what the proper evaulation order/return codes should be for this case. Both 403/400 are failures and cause CORS to fail so there should be no difference but...