RBAC: allow listing permissions on the root folder (#82184)

* allow returning AC metadata for the root folder

* add a test

* share the reserved root folder UID with frontend

pkg/services/folder/folderimpl/folder.go

@@ -179,6 +179,10 @@ func (s *Service) Get(ctx context.Context, q *folder.GetFolderQuery) (*folder.Fo
 		return nil, folder.ErrBadRequest.Errorf("missing signed in user")
 	}
 
+	if q.UID != nil && *q.UID == accesscontrol.GeneralFolderUID {
+		return folder.RootFolder, nil
+	}
+
 	if s.features.IsEnabled(ctx, featuremgmt.FlagNestedFolders) && q.UID != nil && *q.UID == folder.SharedWithMeFolderUID {
 		return folder.SharedWithMeFolder.WithURL(), nil
 	}
@@ -478,7 +482,7 @@ func (s *Service) deduplicateAvailableFolders(ctx context.Context, folders []*fo
 }
 
 func (s *Service) GetParents(ctx context.Context, q folder.GetParentsQuery) ([]*folder.Folder, error) {
-	if !s.features.IsEnabled(ctx, featuremgmt.FlagNestedFolders) {
+	if !s.features.IsEnabled(ctx, featuremgmt.FlagNestedFolders) || q.UID == accesscontrol.GeneralFolderUID {
 		return nil, nil
 	}
 	if q.UID == folder.SharedWithMeFolderUID {

pkg/services/folder/folderimpl/folder_test.go

@@ -299,6 +299,17 @@ func TestIntegrationFolderService(t *testing.T) {
 				require.NoError(t, err)
 			})
 
+			t.Run("When get folder by uid and uid is general should return the root folder object", func(t *testing.T) {
+				uid := accesscontrol.GeneralFolderUID
+				query := &folder.GetFolderQuery{
+					UID:          &uid,
+					SignedInUser: usr,
+				}
+				actual, err := service.Get(context.Background(), query)
+				require.Equal(t, folder.RootFolder, actual)
+				require.NoError(t, err)
+			})
+
 			t.Run("When get folder by title should return folder", func(t *testing.T) {
 				expected := folder.NewFolder("TEST-"+util.GenerateShortUID(), "")
 

pkg/services/folder/model.go

@@ -53,7 +53,7 @@ type Folder struct {
 }
 
 var GeneralFolder = Folder{ID: 0, Title: "General"}
-
+var RootFolder = &Folder{ID: 0, Title: "Root", UID: GeneralFolderUID, ParentUID: ""}
 var SharedWithMeFolder = Folder{
 	Title:       "Shared with me",
 	Description: "Dashboards and folders shared with me",