Alerting: Rule version history API (#99041)

* implement store method to read rule versions

* implement request handler

* declare a new endpoint

* fix fake to return correct response

* add tests

* add integration tests

* rename history to versions

* apply diff from swagger CI step

Signed-off-by: Yuri Tseretyan <yuriy.tseretyan@grafana.com>

---------

Signed-off-by: Yuri Tseretyan <yuriy.tseretyan@grafana.com>

pkg/services/ngalert/store/compat_test.go

@@ -43,3 +43,20 @@ func TestAlertRuleToModelsAlertRule(t *testing.T) {
 		require.Equal(t, ngmodels.ErrorErrState, converted.ExecErrState)
 	})
 }
+
+func TestAlertRuleVersionToAlertRule(t *testing.T) {
+	g := ngmodels.RuleGen
+
+	t.Run("make sure no data is lost between conversions", func(t *testing.T) {
+		for _, rule := range g.GenerateMany(100) {
+			// ignore fields
+			rule.DashboardUID = nil
+			rule.PanelID = nil
+
+			r, err := alertRuleFromModelsAlertRule(rule)
+			require.NoError(t, err)
+			r2 := alertRuleVersionToAlertRule(alertRuleToAlertRuleVersion(r))
+			require.Equal(t, r, r2)
+		}
+	})
+}