Automatically nag inactive infra bugs with non-backlog-priority

[lukebjerring]

Context: https://foolip.github.io/ecosystem-infra-rotation/

We have a rotation that ensures that we're triaging bugs labelled infra. For the criteria that produces the list of stale bugs, that are actually assigned, it would be good to automate the process of "Friendly ping, are you working on this?" which is currently a time-consuming human activity.

cc @foolip

[foolip]

I'm doing the rotation this week, and https://github.com/web-platform-tests/wpt/issues/14467 was the first that I handled. Quite often I end up changing the priority instead of just nagging.

I guess the problem is that not everyone has context on the issues, and yet everyone is asked to help nag?