The cli package is meant for single-shot execution anyway, so
instead of plumbing everything through reentrantly, let's just
have a global you can seed before calling CLI().
The two binaries (Apache2 and GPL) both invoke the cli package to do
the work, the only difference between them is that the GPL binary passes
it embedded ipxe binaries.
In practice, most people will want the standalone binary that Just
Works, the variant that doesn't embed ipxe is going to be for niche
applications only.
This version is still *extremely* barebones, and the unstable tag
in the README applies triple for it, but the code in its current
state is capable of booting x86 and UEFI clients correctly, and
that was hard enough to merit a snapshot checkpoint.
