Preconfigure Qt File Open/Save dialog

`~/.config/QtProject.conf` contains shortcuts for the left-side pane in File Open/Save dialogs.

Unfortunately the full path (incuding the username) is hardcoded there, and `~` and `$HOME` do not seem to work.

So, how can we preconfigure this file in `/usr/local/share/skel/`?

We would like to put in links to things like Applications, Desktop, Documents, Downloads, and so on.

Also we would like to configure Qt File Open/Save dialog to respect `.hidden` files by default.