Except a short whitelist of system libraries, we should have always set
rpath so that the slapos version of the library is used.

We had issues with components which where compiled with slapos version
of openssl but linked without rpath. At runtime they were using system
openssl.

Rewrite our complex grep shell pipeline in python, with a function
parsing ldd output so that we can check not only for not found dynamic
libraries, but also for libraries that are found outside of slapos
library dirs.

This also fixes problems that this grep pipeline did not support paths
with spaces in their names.

Fix long lines, incorrect type annotations and adjust a bit to make mypy
happy.

Sometimes instanciation fail because some service do not start and the
"check port listening" promises fail. In this case, it's very important
to also have the partition content to see what's in the log files.

/reviewed-on nexedi/slapos.core!175

To isolate log files per test in the snapshots

Log files from slapos node software are large and they are always the
same after each test method, so it does not make much sense to store
them for each test method snapshot, because we only run slapos node
software at setupModule step.

Log files from slapos node instance are smaller, but it's also not
needed to make a snapshot after each test, because we only run slapos
node instance at setUpClass step.

To prevent duplication, store slapos log files only at setupModule (for
software) and at setUpClass (for instance).

Also store log slapos log files in all the steps that can fail in
_cleanup.

Everything in etc can be interesting while investigating issues in
test, also it should not be too big.

It's also interesting to see what scripts have been generated

Keeping buildout.cfg and .installed.cfg can help diagnosing test
failures.

Directories were ignored by mistake, we found out that several files
that would help us diagnosing problems were missing, because we only
snapshot etc/* which did not snapshot recursive directories such as
etc/promise or etc/service.

Symlinks were copied (the target was copied), because they matched the
isfile check, but if the symlink target was not existent, this caused
errors.

Also rename _snapshot_instance_file to _copySnapshot as it is no longer
treating files only

supervisor configuration is interesting to inspect in, the same for runners
in run and service directories.

/reviewed-on nexedi/slapos.core!170

/reviewed-on nexedi/slapos.core!150

- We should only try to remove leaked partitions if we detected some,
  otherwise it may produce a strange message "unable to delete leaked
  partitions".
- If some supervisor configuration is still present after partition
  deletion, they must be removed not to block next test and the current
  test must be marked failed.

Quite often when test fail we don't have any information about what was
wrong with the tested instance. Dumping the generated etc/* files and
the instance log files should help diagnosing such errors.

This command sometimes fail, for example with:

  2019-10-23 06:10:56 slapos[27556] ERROR
  Traceback (most recent call last):
    File "slapos/grid/SlapObject.py", line 800, in destroy
      self.cleanupFolder(self.instance_path)
    File "slapos/grid/SlapObject.py", line 836, in cleanupFolder
      os.remove(os.path.join(folder_path, file))
  FileNotFoundError: [Errno 2] No such file or directory: 'tmp/inst/defp5/.installed.cfg.tmp'

otherwise logged error and critical messages are just ignored.