Adding label and logging when paths aren't matched

[vvolkgang]

Description:

Handle paths that weren't matched by adding a label and logging (and commenting?) the list of missed paths, so the labeler file can be easily updated.

Justification:
I need all my paths to be labeled or ignored and with ongoing development it will be hard to maintain unless we have systems in place raising visibility of missing paths. #79 doesn't solve this, ideally this would happen for all PRs regardless of the file status.

Are you willing to submit a PR?
Yes, but, TS isn't my tool of trade and when I looked into v4.0.3, it seemed to require inverting the whole process, figured someone who knew the codebase better could come up with a less invasive solution. I've yet to look again since then and I'm not sure if it would be easier with the V5 changes.

[MaksimZhukov]

Hello @vvolkgang!
Thank you for creating the feature request!
Have you seen this issue? Is that what you're asking for?

[vvolkgang]

@MaksimZhukov saw it but scrubbed it off as a logging improvement in general. I can definitely see how both overlap, although the focus here is the label.

[duffzm]

this would be a great feature