feat(nested folders): add CountDashboardsInFolder (#57847)

* feat(nested folders): add CountDashboardsInFolder

This commit adds a new method to the Dashboard service and stores: CountDashboardsInFolder. The command struct takes a folderUID, but the store implementation still depends on the parent folder ID. This is temporary; eventually we will replace all references to FolderIDs (associated with Dashboards) with folder UIDs.

There are some unfortunate additional test changes that were necessary after generating the service & store mocks; it looks like that hasn't been generated since the last change(s).

* more test updates
* don't forget the service test
* that didn't end up used, so bye for now
* agree to disagree with the linter

pkg/services/dashboards/database/database.go

@@ -1017,3 +1017,18 @@ func (d *DashboardStore) GetDashboardTags(ctx context.Context, query *models.Get
 		return err
 	})
 }
+
+// This will be updated to take CountDashboardsInFolderQuery as an argument and
+// lookup dashboards using the ParentFolderUID when the NestedFolder
+// implementation is complete.
+func (d *DashboardStore) CountDashboardsInFolder(
+	ctx context.Context, req *dashboards.CountDashboardsInFolderRequest) (int64, error) {
+	var dashboards = make([]*models.Dashboard, 0)
+	err := d.store.WithDbSession(ctx, func(sess *db.Session) error {
+		session := sess.In("folder_id", req.FolderID).In("org_id", req.OrgID).
+			In("is_folder", d.store.GetDialect().BooleanStr(false))
+		err := session.Find(&dashboards)
+		return err
+	})
+	return int64(len(dashboards)), err
+}