This reverts commit cac0cb7f02.
This doesn't work since CI currently mixes flatpak-builder and the host git repo
and doesn't download the gtk sources, so all subprojects are missing.
Instead of building the projects from my forks, build them as gtk
subprojects.
To avoid meson hitting the network for those wraps, add the required
files as extra sources and put them into subprojects/packagecache,
so meson can find them at build time.
We have a tight coupling with pango, whenever new
pango API appears, our build usually breaks. So
just make our flatpak manifests build pango from git.
Downloading the subproject during the GTK build fails
in a flatpak build due to lack of network access.
flatpak-builder insists on having these things explicitly
spelled out as dependencies.
We are building against the 3.32 sdk, which has
a new-enough glib to default to the keyfile
settings backend.
Also, use fallback-x11, so we prefer Wayland.
