Add author filter

[aocenas]

Closes: #192
Maybe also: #264

Adds a regex filter that checks author of a PR so you can do same regex filtering on it as with title. It uses i.GetUser().Login as the string to match (so cannot be used on full name but that does not seem important).

Our usecase for this is to have a table with team PRs and separate ones for external ones. This usecase would also be served by #266 to be honest but I did not notice it before and I think this may still be useful.

The code is just copy pasting existing regex filters code.

This is a draft mainly to check the naming and get some feedback on whether I am forgetting to add something somewhere to make this work consistently, naming etc.

TODO:

• docs
• ???

[google-cla]

Thanks for your pull request. It looks like this may be your first contribution to a Google open source project (if not, look below for help). Before we can look at your pull request, you'll need to sign a Contributor License Agreement (CLA).

📝 Please visit https://cla.developers.google.com/ to sign.

Once you've signed (or fixed any issues), please reply here with @googlebot I signed it! and we'll verify it.

---

What to do if you already signed the CLA

Individual signers

• It's possible we don't have your GitHub username or you're using a different email address on your commit. Check your existing CLA data and verify that your email is set on your git commits.

Corporate signers

• Your company has a Point of Contact who decides which employees are authorized to participate. Ask your POC to be added to the group of authorized contributors. If you don't know who your Point of Contact is, direct the Google project maintainer to go/cla#troubleshoot (Public version).
• The email used to register you as an authorized contributor must be the email used for the Git commit. Check your existing CLA data and verify that your email is set on your git commits.
• The email used to register you as an authorized contributor must also be attached to your GitHub account.

ℹ️ Googlers: Go here for more info.

[aocenas]

@googlebot I signed it!

[aocenas]

Hey, @tstromberg any feedback on this? Or should I change it from draft to regular PR?

[meltsufin]

@aocenas Thanks for a shoutout to #266. We've been using it for a few weeks now and it's been working great. I'm still waiting for a followup on the PR though.

[RCheesley]

Nice, thanks for making the PR! We have the same need but slightly different use case, we need it to enable us to filter PRs by certain organisations so that other orgs can target those ones for testing (we have rules that you can't test PRs from your own company).

Happy to test if someone could explain in simple terms how to :)

[RCheesley]

@aocenas is there any possibility you could share an example of how you're using this on your panels? Would love to help with testing but without the docs to explain how to implement I'm a bit stuck.

[joeyparrish]

@aocenas, are you interested in reviving this PR? If so, let's discuss. I've just been made a maintainer of this project, and though I'm new to the codebase, I'd be happy to discuss this and work with you on a solution.