now that we use haproxy on the frontend, this is OK

We will not do this

This reverts commit 466ff9fe.

Using an script to set the environment is easier to use, but the main
reason is that if we want to be able to use shared part from outer
slapos (like when using in theia or slaprunner), the working directory
for test must be contained in the instance directory of the outer
slapos, so that when we run slapos node prune in the outer slapos this
command can see that shared parts are used.

version up to current version (0.13.0) and include configuration to make use of nexedi/slapos.core!218

Also switch to gopls and include jdk, with all preliminary support for patchelf.

See merge request nexedi/slapos!774

we need the patch to be able to build with gcc 10 (used on Archlinux for example).
See https://bugs.gentoo.org/705898
patch is coming from https://705898.bugs.gentoo.org/attachment.cgi?id=603950

When running tasks, shell is invoked like:

   $THEIA_SHELL -c "command with arguments that\ can\ contain\ spaces"

The version from theia images does not support running from a plugin
installed in a read only folder, this newest version seem to work.

Also set the required java.home setting

So that gitlens extension (which can be installed per-workspace) knows
how to open files from lab.nexedi.com in browser

so that we can easily use python version 2 or 3 during development and
local testing.

This python is not directly usable with python extension, pip needs to
be installed as user, following:
https://pip.pypa.io/en/stable/installing/#installing-with-get-pip-py

by logging the process output

so that frontend requests are requested as theia computer partition.
Practically this means that if theia is installed on slapos master,
frontend requests for slapos inside theia partition will be requested as
this theia instance.

When updated to 4.8.1 the cursor "shadow" rendering is incorrect

workaround for https://github.com/eclipse-theia/theia/issues/8158

So that parts are shared when we install ERP5 in theia

Not much tested but it looks working

Even if we don't use this, the debug pane cause an error when jdk is not
installed

Some optional extensions installable from the registry (like the XML
supports from redhat) also need java and it's better to have something
to edit XML

extracted from nexedi/slapos!735

there was a mistake in 2de4c80f, we
should sleep for the min duration of these two

This reverts commit 1bd4fc32

Frontend can now do SSL client authentication to the backend. This is turned
off by default, but easy to enable by proper switch.

In order to achieve this result haproxy has been introduced as middleman just
before the backend. Also it came with rsyslogd, as haproxy can't log by
itself.

Documentation has been updated, also changelog has been introduced.

A lot of additional tests has been added due to adding additional component
(haproxy) which required a bit different ways to approach to the request input
data.

See merge request nexedi/slapos!771