RBAC: Add required component to perform access control checks for user api when running single tenant (#93104)

* Unexport store and create new constructor function

* Add ResourceAuthorizer and LegacyAccessClient

* Configure checks for user store

* List with checks if AccessClient is configured

* Allow system user service account to read all users

---------

Co-authored-by: Gabriel MABILLE <gamab@users.noreply.github.com>

pkg/services/accesscontrol/mock/mock.go

@@ -265,3 +265,8 @@ func (m *Mock) SyncUserRoles(ctx context.Context, orgID int64, cmd accesscontrol
 	}
 	return nil
 }
+
+// WithoutResolvers implements fullAccessControl.
+func (m *Mock) WithoutResolvers() accesscontrol.AccessControl {
+	return m
+}