Merge branch 'mptcp-cleanup-and-improvements-in-the-selftests'

Matthieu Baerts says:

====================
mptcp: cleanup and improvements in the selftests

This small series of 4 patches adds some improvements in MPTCP
selftests:

- Patch 1 reworks the detailed report of mptcp_join.sh selftest to
  better display what went well or wrong per test.

- Patch 2 adds colours (if supported, forced and/or not disabled) in
  mptcp_join.sh selftest output to help spotting issues.

- Patch 3 modifies an MPTCP selftest tool to interact with the
  path-manager via Netlink to always look for errors if any. This makes
  sure odd behaviours can be seen in the logs and errors can be caught
  later if needed.

- Patch 4 removes stdout and stderr redirections to /dev/null when using
  pm_nl_ctl if no errors are expected in order to log odd behaviours.
====================

Link: https://lore.kernel.org/r/20230730-upstream-net-next-20230728-mptcp-selftests-misc-v1-0-7e9cc530a9cd@tessares.net
Signed-off-by: Jakub Kicinski <kuba@kernel.org>