Add option to show folders after files

[newhinton]

Is your feature request related to a problem? Please describe.
It would be nice if the filepicker could reach parity with the octoprint one.
For that i would like to see the ability to show files before folders.
This would allow the user to quickly print the latest uploaded file in the rootfolder instead of having to scroll past folders.

Describe the solution you'd like
An additional checkbox in the sort order menu.

Additional context
Related to #226