Service Accounts: Display name to ID (#46258)

* ServiceAccounts: modernize SA creation interface

* ServiceAccounts: improve service account ID generation

* ServiceAccounts: remove unused method

* ServiceAccounts: Make SA ID display name dependent

* ServiceAccounts: Add tests for Service Account creation

* trim trailing whitespace

* Update pkg/services/serviceaccounts/api/api.go

Co-authored-by: Ieva <ieva.vasiljeva@grafana.com>

* Update pkg/services/serviceaccounts/api/api.go

Co-authored-by: Ieva <ieva.vasiljeva@grafana.com>

pkg/services/serviceaccounts/database/errors.go

@@ -6,6 +6,17 @@ import (
 	"github.com/grafana/grafana/pkg/models"
 )
 
+type ErrSAInvalidName struct {
+}
+
+func (e *ErrSAInvalidName) Error() string {
+	return "service account name already in use"
+}
+
+func (e *ErrSAInvalidName) Unwrap() error {
+	return models.ErrUserAlreadyExists
+}
+
 type ErrMisingSAToken struct {
 }