mail,mpv,qutebrowser,vifm: Fix small issues

Added videos directory to vifm quick marks (`v`).

Fixed (hopefully) qutebrowser statusbar hiding and showing.

Improved mail checking script password file handling by switching the
hard-coded path to one still somewhat hard-coded, but encapsulated in a
variable to make changing it later on easier. The script is a bit
slap-dash anyway, so when refactored should be refactored overall.

Added `gallery-dl` handling by mpv, whenever a link starting with
`gdl://` is passed in.

vifm/.config/vifm/vifmrc

@@ -120,6 +120,7 @@ mark d ~/downloads/
 mark p ~/projects/
 mark s ~/projects/studentassistant/
 mark i ~/pictures/
+mark v ~/videos/
 mark n ~/documents/notes/
 mark N ~/Nextcloud/
 mark l ~/documents/library/academia/pdf/