WIP: Add SteamRT 2 'spy'

https://phabricator.collabora.com/T12897

Requires:

• !1 (closed)
• steam/base-files!7
• steam/coreutils!1
• steam/curl!2
• steam/dconf!2
• steam/steamrt-spy/findutils!1
• steam/flatpak-xdg-utils!2
• steam/fontconfig!2
• steam/steamrt-spy/gcc-7!1
• steam/steamrt-spy/gcc-8!1
• steam/steamrt-spy/gcc-defaults!1
• steam/glibc!3
• steam/gtk_2.0!2
• steam/gtk_3.0!1
• steam/hostname!2
• steam/pam!2
• steam/steamrt-spy/pkg-kde-tools!1
• steam/shadow!3
• steam/steamrt!5
• steam/util-linux!3
• steam/xterm!3