Identity: Use typed version of namespace id (#87257)

* Remove different constructors and only use NewNamespaceID

* AdminUser: check typed namespace id

* Identity: Add convinient function to parse valid user id when type is either user or service account

* Annotations: Use typed namespace id instead

pkg/services/accesscontrol/authorize_in_org_test.go

@@ -186,7 +186,7 @@ func TestAuthorizeInOrgMiddleware(t *testing.T) {
 			req := httptest.NewRequest(http.MethodGet, "/api/endpoint", nil)
 
 			expectedIdentity := &authn.Identity{
-				ID:          authn.MustNewNamespaceID(authn.NamespaceUser, tc.ctxSignedInUser.UserID),
+				ID:          authn.NewNamespaceID(authn.NamespaceUser, tc.ctxSignedInUser.UserID),
 				OrgID:       tc.targetOrgId,
 				Permissions: map[int64]map[string][]string{},
 			}