add a right click menu for item

I think DataManager should remove the dirents cache of the current path when the request finishes successfully.

Consider this sequence:

1. User deletes a file in root folder `/`
2. Before the delete request finishes, user navs to the folder `/foo`
3.  The delete request finishes, and the user navs back to `/`
4.   Now the dirents cache of `/` is stale.