testrun crashes unnecessarily due to package / skipsdist handling

[Oliver Bestwalter]

The way this is handled currently is plain wrong. If any testenv is marked as direct via envname or testenv attribute and a non-direct testenv is invoked, this happens:

Traceback (most recent call last):
  File "/home/ob/oss/tox-dev/tox-direct/.venv/bin/tox", line 8, in <module>
    sys.exit(cmdline())
  File "/home/ob/oss/tox-dev/tox-direct/.venv/lib/python3.8/site-packages/tox/session/__init__.py", line 44, in cmdline
    main(args)
  File "/home/ob/oss/tox-dev/tox-direct/.venv/lib/python3.8/site-packages/tox/session/__init__.py", line 69, in main
    exit_code = session.runcommand()
  File "/home/ob/oss/tox-dev/tox-direct/.venv/lib/python3.8/site-packages/tox/session/__init__.py", line 197, in runcommand
    return self.subcommand_test()
  File "/home/ob/oss/tox-dev/tox-direct/.venv/lib/python3.8/site-packages/tox/session/__init__.py", line 225, in subcommand_test
    run_sequential(self.config, self.venv_dict)
  File "/home/ob/oss/tox-dev/tox-direct/.venv/lib/python3.8/site-packages/tox/session/commands/run/sequential.py", line 9, in run_sequential
    if venv.setupenv():
  File "/home/ob/oss/tox-dev/tox-direct/.venv/lib/python3.8/site-packages/tox/venv.py", line 628, in setupenv
    status = self.update(action=action)
  File "/home/ob/oss/tox-dev/tox-direct/.venv/lib/python3.8/site-packages/tox/venv.py", line 270, in update
    self.hook.tox_testenv_create(action=action, venv=self)
  File "/home/ob/oss/tox-dev/tox-direct/.venv/lib/python3.8/site-packages/pluggy/hooks.py", line 286, in __call__
    return self._hookexec(self, self.get_hookimpls(), kwargs)
  File "/home/ob/oss/tox-dev/tox-direct/.venv/lib/python3.8/site-packages/pluggy/manager.py", line 93, in _hookexec
    return self._inner_hookexec(hook, methods, kwargs)
  File "/home/ob/oss/tox-dev/tox-direct/.venv/lib/python3.8/site-packages/pluggy/manager.py", line 84, in <lambda>
    self._inner_hookexec = lambda hook, methods, kwargs: hook.multicall(
  File "/home/ob/oss/tox-dev/tox-direct/.venv/lib/python3.8/site-packages/pluggy/callers.py", line 208, in _multicall
    return outcome.get_result()
  File "/home/ob/oss/tox-dev/tox-direct/.venv/lib/python3.8/site-packages/pluggy/callers.py", line 80, in get_result
    raise ex[1].with_traceback(ex[2])
  File "/home/ob/oss/tox-dev/tox-direct/.venv/lib/python3.8/site-packages/pluggy/callers.py", line 187, in _multicall
    res = hook_impl.function(*args)
  File "/home/ob/oss/tox-dev/tox-direct/src/tox_direct/hookimpls.py", line 90, in tox_testenv_create
    raise NormalEnvNeedsPackage(
tox_direct.hookimpls.NormalEnvNeedsPackage: NormalEnvNeedsPackage: [tox-direct] FATAL: tox env 'publish' needs a package.
Do not run this env as part of a direct run or run everything in the host (including package build) by running with --direct-yolo flag.
WARNING: this will change the host environment.

This happens only because the check if a testrun is direct looks at all testenvs instead of only the ones that are part of the current run.

It is also not necessary to crash at all, when skipsdist is handled more intelligently.

https://github.com/obestwalter/tox-direct/tree/refactor-and-make-less-dumb contains a sketch general improvements and a fix for this problem.