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

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

pkg/registry/apis/iam/legacy/user_internal_id.sql

@@ -0,0 +1,7 @@
+SELECT u.id
+FROM {{ .Ident .UserTable }} as u
+INNER JOIN {{ .Ident .OrgUserTable }} as o ON u.id = o.user_id
+WHERE o.org_id = {{ .Arg .Query.OrgID }}
+AND u.uid = {{ .Arg .Query.UID }}
+AND NOT u.is_service_account
+LIMIT 1;