guestfish: Add guestfish front-end.

This is a Python rewrite of the guestfish front-end from the
original ostbuild which is now (almost) entirely written with gjs.
qa_make_disk: Builtin action to make disks.

Python rewrite of the qa_make_disk builtin found on the original
ostbuild which is now (almost) entirely written with gjs.
qa_pull_deploy: Builtin action to deploy a repository.

Python rewrite of qa_pull_deploy found on the original ostbuild
repository which is now (almost) entirely written in gjs.
libqa: Simple QA library, WIP.

Python rewrite of libqa.js found on the origina ostbuild repository
which is now (almost) entirely written in gjs.

This library does nothing for now.
Add the new builtins to the makefile.
fileutil: Simple function to find a program in path.

This function is very useful when we need to find the full path
of a program given a PATH environment variable.
qa_smoke_test: Basic smoke test.

Python rewrite of the one found on the original ostbuild repository
which is now (almost) entirely written in gjs.