IAM: Add email, login field validation to User create/update API (#112391)

* wip

* wip

* wip

(cherry picked from commit 8cedf25892)

* Search seems to be working, the validation is still wip

* Use keyword.Name analyzer for Filterable fields

* Only string fields should be indexed with keyword analyzer

* Change search query for email and login fields to use term query
* Remove unnecessary Exact from the resource protobuf definitions

Co-Authored-By: Ryan McKinley <ryantxu@gmail.com>

* Add legacy search support to the API

* Tests for legacy search, validate and integration tests for user

* Lint

* Add snapshot tests to userDocumentBuilder

* Address CodeQL issues

* Improvements, handle Mode2, tests should pass

* Change default limit from 0 to 1 for requests

* Cleanup

* Add fixme

* Update pkg/registry/apis/iam/register.go

Co-authored-by: Stephanie Hingtgen <stephanie.hingtgen@grafana.com>

* Update pkg/registry/apis/iam/user/legacy_search.go

Co-authored-by: Stephanie Hingtgen <stephanie.hingtgen@grafana.com>

---------

Co-authored-by: Ryan McKinley <ryantxu@gmail.com>
Co-authored-by: Stephanie Hingtgen <stephanie.hingtgen@grafana.com>

pkg/registry/apis/iam/models.go

@@ -13,7 +13,9 @@ import (
 	"github.com/grafana/grafana/pkg/services/authz/zanzana"
 	"github.com/grafana/grafana/pkg/services/featuremgmt"
 	"github.com/grafana/grafana/pkg/services/ssosettings"
+	"github.com/grafana/grafana/pkg/storage/legacysql/dualwrite"
 	"github.com/grafana/grafana/pkg/storage/unified/resource"
+	"github.com/grafana/grafana/pkg/storage/unified/resourcepb"
 )
 
 var _ builder.APIGroupBuilder = (*IdentityAccessManagementAPIBuilder)(nil)
@@ -59,6 +61,10 @@ type IdentityAccessManagementAPIBuilder struct {
 	reg    prometheus.Registerer
 	logger log.Logger
 
+	dual             dualwrite.Service
+	unified          resource.ResourceClient
+	userSearchClient resourcepb.ResourceIndexClient
+
 	// non-k8s api route
 	display *user.LegacyDisplayREST