Files View: Sort Order Column "Relative Directory"

To easy working with Merge Requests in Gitlab the order of sorting the column "relative directory" in "Files" View should be configurable. 

Current state as of 22.1.3 shows files in top folder first and iterates to nested folders afterwards. Gitlab web view sorting follows nested directories first and top folders last.

```

# Example: Current state

# descending

/root/.gitignore

/root/filea

/root/fileb

/root/directorya/filea

/root/directorya/directoryb/filec

/root/directoryb/filea

/root/directoryb/directoryb/filec

#ascending

/root/directoryb/directoryb/filec

/root/directoryb/filea

/root/directorya/directoryb/filec

/root/directorya/filea

/root/fileb

/root/filea

/root/.gitignore

#Desired state:

#Gitlab Webview sorting:

/root/directorya/directoryb/filec

/root/directorya/filea

/root/directoryb/directoryb/filec

/root/directoryb/filea

/root/.gitignore

/root/filea

/root/fileb

```

Just inverting the sort direction (ascending / descending) doesn't work since it would also invert the alphabet of folders