Gracefully handle eval() failure(s) for marker expressions

[symonk]

Hello pytest devs, great project thanks and I look forward to growing my contributions, tho its quite the code base to understand! from #4583 this provides a nicer error message to the user when invoking eval() for marker expressions does not go quite successfully, raising a USAGE_ERROR rather than the crash/INTERNAL_ERROR at present.

Thank you very much for taking your time to review my PR, look forward to addressing any feedback, have a great day.

• Allow maintainers to push and squash when merging my commits. Please uncheck this if you prefer to squash the commits yourself.
• Create a new changelog file in the changelog folder, with a name like `.
• Add yourself to AUTHORS in alphabetical order.

[bluetech]

Thanks again @symonk! I left a couple of comments.

We have some discussion on a more comprehensive solution to eval issues at issue #6822 if you're interested. This however should not prevent us from making the current situation better.

[symonk]

appreciate the feedback, updated and ran tox locally to verify

[bluetech]

@symonk I would have liked to invite you to join the development team, however I don't seem to have the permissions for that. So I hope someone who does reads this and does so :)