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/services/ngalert/api/api_prometheus.go

@@ -304,7 +304,7 @@ func (srv PrometheusSrv) toRuleGroup(groupKey ngmodels.AlertRuleGroupKey, folder
 	newGroup := &apimodels.RuleGroup{
 		Name: groupKey.RuleGroup,
 		// file is what Prometheus uses for provisioning, we replace it with namespace which is the folder in Grafana.
-		File: folder.Title,
+		File: ngmodels.GetNamespaceKey(folder.ParentUID, folder.Title),
 	}
 
 	rulesTotals := make(map[string]int64, len(rules))