feat: move auth providers behind ee token (#48245)

* feat: move auth providers behind ee token

Fixes #48235

Introduces new premium feature `database-auth-providers`.
Moves fetch-auth behind defenterprise - oss will always return an empty
map.
Add metabase.util.http to test outbound http requests.

* Fix broken refs

* Drop defmethod as adhoc overrides aren't desirable outside ee

* Drop unessary require

* Fix token and tests

* Fix tests

* Fix formatting

* Fix var cast exception

* Fix connection test

* Move test to ee namespace

* Move more tests behind enterprise

* Fix checked-section hiding