Feature setup show

[sallner]

After implementing --setup-only and --setup-plan it seemed to be reasonable to also include an option to show the fixture setup and teardown, while actually executing the tests.

Here's a quick checklist that should be present in PRs:

• Target: for bug or doc fixes, target master; for new features, target features
• Make sure to include one or more tests for your change
• Add yourself to AUTHORS
• Add a new entry to the CHANGELOG (choose any open position to avoid merge conflicts with other PRs)

[coveralls]

Coverage increased (+0.005%) to 92.095% when pulling 6438895 on sallner:feature-setup-show into 7927dff on pytest-dev:features.

[nicoddemus]

Thanks @sallner! 😁