[cubicweb-ctl] move to accepting only once instance name per command The rationals behind this decision are: - while in the past managing all instances sytem wide made a lot of sens, pratices have evolved today and we've moved to managing one instance by one - this makes things easier to debug since commands since using them on several instances were making this harder (errors hidden in the middle) - also solve the problem of the return code to have, before it was always 0 which prevented to do things like: ipython --pdb $(which cubicweb-ctl) $command $instance or shell scripts that used it - this simplify the code and is always good to take

[pkg] Run all unit tests in autopkgtest We previously forgot to copy `tox.ini` alongside the tests. As this file configures pytest pattern matching rules, we were not running quite a few tests. This is now fixed. The added tests required some adjustments in the Debian dependencies. Sadly, not all tests currently pass. It seems there are some ordering dependencies between the tests in regards to how data are loaded. Fixing this probably would probably be better debugged by ensuring the test suite does not fail when using pytest random-order plugin.

[pkg] Stop running unit tests from skeleton The test files shipped as part as the skeleton for `cubeweb-ctl newcube` are not meant to be run as part of our test suite!