Alerting: Update rule API to address folders by UID (#74600)

* Change ruler API to expect the folder UID as namespace

* Update example requests

* Fix tests

* Update swagger

* Modify FIle field in /api/prometheus/grafana/api/v1/rules

* Fix ruler export

* Modify folder in responses to be formatted as <parent UID>/<title>

* Add alerting test with nested folders

* Apply suggestion from code review

* Alerting: use folder UID instead of title in rule API (#77166)

Co-authored-by: Sonia Aguilar <soniaaguilarpeiron@gmail.com>

* Drop a few more latent uses of namespace_id

* move getNamespaceKey to models package

* switch GetAlertRulesForScheduling to use folder table

* update GetAlertRulesForScheduling to return folder titles in format `parent_uid/title`.

* fi tests

* add tests for GetAlertRulesForScheduling when parent uid

* fix integration tests after merge

* fix test after merge

* change format of the namespace to JSON array

this is needed for forward compatibility, when we migrate to full paths

* update EF code to decode nested folder

---------

Co-authored-by: Yuri Tseretyan <yuriy.tseretyan@grafana.com>
Co-authored-by: Virginia Cepeda <virginia.cepeda@grafana.com>
Co-authored-by: Sonia Aguilar <soniaaguilarpeiron@gmail.com>
Co-authored-by: Alex Weaver <weaver.alex.d@gmail.com>
Co-authored-by: Gilles De Mey <gilles.de.mey@gmail.com>

pkg/tests/api/alerting/testing.go

@@ -19,6 +19,7 @@ import (
 
 	"github.com/grafana/grafana/pkg/api"
 	"github.com/grafana/grafana/pkg/expr"
+	"github.com/grafana/grafana/pkg/services/folder"
 	apimodels "github.com/grafana/grafana/pkg/services/ngalert/api/tooling/definitions"
 	ngmodels "github.com/grafana/grafana/pkg/services/ngalert/models"
 	"github.com/grafana/grafana/pkg/services/quota"
@@ -260,9 +261,20 @@ func (a apiClient) ReloadCachedPermissions(t *testing.T) {
 }
 
 // CreateFolder creates a folder for storing our alerts, and then refreshes the permission cache to make sure that following requests will be accepted
-func (a apiClient) CreateFolder(t *testing.T, uID string, title string) {
+func (a apiClient) CreateFolder(t *testing.T, uID string, title string, parentUID ...string) {
 	t.Helper()
-	payload := fmt.Sprintf(`{"uid": "%s","title": "%s"}`, uID, title)
+	cmd := folder.CreateFolderCommand{
+		UID:   uID,
+		Title: title,
+	}
+	if len(parentUID) > 0 {
+		cmd.ParentUID = parentUID[0]
+	}
+
+	blob, err := json.Marshal(cmd)
+	require.NoError(t, err)
+
+	payload := string(blob)
 	u := fmt.Sprintf("%s/api/folders", a.url)
 	r := strings.NewReader(payload)
 	// nolint:gosec