presentation: Fix call to GnomeDesktop.RRScreen

We were providing an extra argument to GnomeDesktop.RRScreen.
This caused a JS error preventing the function from
continuing. After this, we needed to allow D-Bus access to
"org.gnome.Mutter.DisplayConfig" in the flatpak in order
to actually present.

Closes #24
1 job for master in 11 minutes and 12 seconds (queued for 3 seconds)
Status Job ID Name Coverage
passed #232396