tests: integrate lcitool for generating build env manifests

tests: integrate lcitool for generating build env manifests

This introduces

  https://gitlab.com/libvirt/libvirt-ci

as a git submodule at tests/lcitool/libvirt-ci

The 'lcitool' program within this submodule will be used to
automatically generate build environment manifests from a definition
of requirements in tests/lcitool/projects/qemu.yml

It will ultimately be capable of generating

 - Dockerfiles
 - Package lists for installation in VMs
 - Variables for configuring Cirrus CI environments

When a new build pre-requisite is needed for QEMU, if this package
is not currently known to libvirt-ci, it must first be added to the
'mappings.yml' file in the above git repo.

Then the submodule can be updated and the build pre-requisite added
to the tests/lcitool/projects/qemu.yml file. Now all the build env
manifests can be re-generated using  'make lcitool-refresh'

This ensures that when a new build pre-requisite is introduced, it
is added to all the different OS containers, VMs and Cirrus CI
environments consistently.

It also facilitates the addition of containers targetting new distros
or updating existing containers to new versions of the same distro,
where packages might have been renamed.

Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20211215141949.3512719-8-berrange@redhat.com>
Message-Id: <20220105135009.1584676-8-alex.bennee@linaro.org>