We can move everything but Liberation fonts build to the container.
Sadly those require newer version of fontforge than the one available in
the Steam RT.
There's some extra logic necessary to assure that font build triggers in
the container with the default/all targets.
This removes the requirement to have afdko and fonttools installed on
the host.
They are metrically compatible with MS Gothic fonts. Attack on Titan 2
- A.O.T.2 - 進撃の巨人2 and Touhou Fuujinroku ~ Mountain of Faith are
known to render better with Ume fonts.
CW-Bug-Id: #19849
CW-Bug-Id: #19971