Load global sysext/confext from /.extra/global_{sysext,confext} which
systemd-stub puts there from ESP/loader/credentials/*.{sysext,confext}.raw.
Global extensions are handled the exact same way as per-UKI ones.
File system modules should be something the kernel can autoload
automatically, and according to my testing that works fine, hence let's
drop the explicit deps, in particular as systems usually stick to one fs
for these things, not both.
I inquired bluca about the reason to add it, and didn't remember
anymore, and was fine with me removing this. So let's remove this for
now, should issues arise we can revert this.
In the initrd we want to run as early as possible, before
any of the filesystems are set up, so that users can use
confexts to customize fstab/veritytab/crypttab/etc. But
in the root fs it needs to run after /var/ has been set
up. Split the unit, and have an initrd-specific one that
runs very early.
