Implementation

I propose to do the following to the typing issues:

1. Add a new label "feature" for feature discussions.
2. Add issue templates for new features (and a few other issue types) so that the correct label gets applied automatically.
3. I volunteer to do housekeeping and go through the old issues in the typing repository, closing out outdated ones and applying the proper labels.
4. As a first step, set up a bot that sends a weekly(?) mail to typing-sig with the titles and links to new feature issues and a list of feature issues that got new comments since the last mail.
5. See how that works out.

I have now implemented steps 1 through 3. All feature suggestions can be found here: https://github.com/python/typing/issues?q=is%3Aissue+is%3Aopen+label%3A%22topic%3A+feature%22

This is a PR for issue templates for the typing repository: https://github.com/python/typing/pull/921 I'm sure that these templates can be improved upon immensely.

Another idea I have: Set up a GitHub Action that closes all feature issues that haven't had new comments for a year or more and have less than 5 comments. If someone still cares about this issue, they can reopen it or leave another comment.

 - Sebastian