See merge request nexedi/slapos!1266

This take another approach at c5cd4e06 (component/glib: set --with-python
to generate scripts with slapos python, 2022-09-20) because this python
might exceed the limit of shebang lines, that change was bad because it
brought back the problem that we fixed in 6acdc8ca (glib: put the expected
python in $PATH, 2019-12-18)

Now that component/defaults.cfg set the ${python:location}/bin in $PATH,
we can assume that python is always in $PATH. The problem with python3
software is that python3 does not install a "python" binary, only python3,
so we can use the $PYTHON environment variable which will be set to
python2 or python3 and that in both cases this will be a valid python
interpreter.

This re-applies 7581b668 (component/glib: remove bad file bin/gtester-report
after compilation, 2020-08-07) because with this approach that script's
shebang is just #!python3

use unshare to create new user-root namesapce to have the perrmission to
create network device, use mount to update files information of network
device in /sys(nemu)
test use iptables to manage route condition, miniupnpd to manage upnp,
brctl(nemu) to create bridge, so add them in component.

add openvpn, add babel, modify ovpn-client/server

due to outdated pypi version, nemu don't include need moudle in
setup.py, so add them in buildout

See merge request nexedi/slapos!1254

Update software/fluent-bit/software.cfg, software/fluent-bit/instance.cfg.in, software/fluent-bit/buildout.hash.cfg files

See merge request nexedi/slapos!1259

see nexedi/slapos.core!418

We were using python2 after extending python2, this explicitly set
python:part = python3

glib configure script uses by default python2.7 to substitute in scripts,
but it also supports --with-python argument. Since the scripts support
python2 or python3, we can use the full path of the python used by
buildout. This will sometimes create shebang lines like:

    #!/usr/bin/env /path/to/slapos/python3/bin/python

but this also work fine.

This replaces the following commits:
 - 7581b668 (component/glib: remove bad file bin/gtester-report after compilation, 2020-08-07)
 - 9c47f828 (componnent/gtk-2: Add python2.7 as the dependency of pango, 2022-08-18)

This removes the need for pytest-testrunner and silent warnings about
its vulnerability in software check

Instead of downloading the image every time before running the test
we pre-download all images during the software installation. This
prevents downloading ~2Go every time, which is sometimes too long for
the slapos node instance step.

Commit changed order of some parameters, which were not reflected in test
updated.

Fixes f0a57a1f

Slaves can disapper during handling of authentication, which will result
with prepared reservation, but with any chance to mark that it's ready.

This was not implemented