Proposal: Stale Bot for auto closing staled issues

[ryou90]

Describe the feature:
There are many staled issues here. It would be helpful if these were automatically closed by a bot to keep a better overview of the importance of issues. For example these could be closed after 2 weeks if not marked as /solved by a maintainer. It also helps other users to see if this issues are solved or not.

Describe a specific use case for the feature:
Issues that are not relevant or the author does not contribute any further information will be closed automatically

[li-boxuan]

Unfortunately, many "stale" issues are still valid, and we don't want to close them. I sometimes manually close issues that are out-of-date, but there's no automatic way to do that without domain knowledge.