wintc_launch_action: use XDG paths for home directories instead of hard-coded English paths

[rozniak]

Oversight during localisation, I used English home directory names in wintc_launch_action. These need to be replaced with XDG directory paths.

Reference: https://docs.gtk.org/glib/enum.UserDirectory.html https://docs.gtk.org/glib/func.get_user_special_dir.html