How to only check for activity by issue author for stale/close counters?

[jeffpaul]

Following on from #887, I would like to configure this action such that a stale label gets applied and then an issue gets closed if there's no response/action by the issue author. The problem is that the action will notice a label being applied, or perhaps other project-based updates by repo maintainers, and view that as activity on an issue and not start the stale/close counters.

Ideally issues would either by default ignore activity except by the issue author, potentially with a flag to change that default.