Full SCIM Identities support for the SCIM API

The SCIM API now supports SCIM Identities in all endpoints
when the `scim_identities` feature flag is enabled for a group.
For now the feature flag remains disabled by default.

ee/spec/lib/ee/gitlab/scim/provisioning_service_spec.rb

@@ -86,6 +86,8 @@ describe ::EE::Gitlab::Scim::ProvisioningService do
             extern_uid: 'test_uid'
           }
         end
+      end
+    end
 
         it 'fails with error' do
           expect(service.execute.status).to eq(:error)