chore: Move Stylelint to GitHub action and fix broken config

[nschonni]

• Swaps Travis for Stylelint step
• Adds the "problem matcher" so issues are commented directly on the lines in PRs
• Fix the styleline config which was in 2 files, and wasn't valid in one, so hasn't been running

[nschonni]

@mcking65 it looks like Stylelint has been broken since the config file changes in #1255
I can submit those changes separately from the CI changeover if you want, but this was useful in also highlighting the things the problem matcher is flagging

[mcking65]

@mcking65 it looks like Stylelint has been broken since the config file changes in #1255

Wow ... interesting. Wonder how that snuck past us.

I can submit those changes separately from the CI changeover if you want, but this was useful in also highlighting the things the problem matcher is flagging

I think a PR to fix the config and change the CI is fine. Thank you for this!

I'll need a few people to look at this. @jongund, this could impact other work in progress, but I don't think in any significant way.

[nschonni]

The remaining issues that I didn't fix was for this rule https://stylelint.io/user-guide/rules/no-descending-specificity
It could either be disabled to get back to green, or it needs to be addressed in the files that are flagged

[spectranaut]

Thanks so much for this! If fixing all the no-descending-specificity is too much for you, then can you push a commit to ignore the rule, and add a comment and an issue?

[nschonni]

@spectranaut good call. I opened #1522, but couldn't add a comment in the RC file, because then it stopped reading it again 😄 . The rule is null'd again for now

[spectranaut]

At least we have the issue :)

[nschonni]

@spectranaut the regression tests don't even like me here

[spectranaut]

@nschonni the regression tests had a strange timeout error I haven't seen before (something like "no new tests in 10 minutes") so I just restarted the job and it passed. This error looks unrelated to the PR and isn't a pattern I've seen anywhere else.

@mcking65 I think this can be merged!