Add bot to close stale issues

There are a growing number of issues which are stale either because they've seen no action or they have been overcome by events (OBE). I recommend adding a bot to automatically track, flag, and eventually close stale issues to help keep this clean:

[https://github.com/marketplace/actions/close-stale-issues](https://github.com/marketplace/actions/close-stale-issues)

We would need to ensure this is Apache friendly, first. We could look to other Apache libraries to see what's used there.

Start with the linked close-stale-issues Marketplace action and inspect comparable automation used by other Apache libraries. Determine an Apache-compatible approach and define how issues are tracked, flagged, and eventually closed; done means qualifying stale or OBE issues receive the intended automated handling.

Written by the indexing model from the issue text.