* Validate authID when user is provisioned
* Add new `user_unique_id` to `user_auth` table
* Validate provisioned user with saml assertion
* Rework `ExternalUID`
* Validate for ExternalUID only
* Enhance verbosity
* Move ExternalUID to saml config
* Rename db variable for externalUID
* Add verbosity to debug ExternalUID
* Assign new error for ExternalUID mismatch
* Add `GetByLoginFn`
* Add new configuration to saml tests
* add validation for empty externalUID