dashfolders: link to folder for inherited permissions

In the permissions view in dashboard settings, this adds a
link to the parent folder for inherited permissions. Which
allows the user to easily navigate to the folder and change
inherited permissions.

pkg/api/dtos/dashboard.go

@@ -26,6 +26,7 @@ type DashboardMeta struct {
 	IsFolder    bool      `json:"isFolder"`
 	FolderId    int64     `json:"folderId"`
 	FolderTitle string    `json:"folderTitle"`
+	FolderSlug  string    `json:"folderSlug"`
 }
 
 type DashboardFullWithMeta struct {