Merged requested to merge i1t/pleroma:923_oauth_consumer_refactoring_ci into develop
Follow-up to !923 (merged), OAuth consumer params handling refactoring.
Registration and authorization-related params are wrapped in "authorization" in order to reduce edge cases number and simplify handling logic. Less error-prone than dealing with
"authorization": ... in some actions and auth-related attrs passed as root
params keys in other actions (previous implementation).