Misc: Add config for lockbot

[dmethvin]

Summary

Adds configuration for the bot described in https://github.com/apps/lock and gh-4069. In addition we'll need to add the bot to the repo's config.

I didn't add a close message because the bot will go through all the closed issues/PRs and lock them. If we add it now we'll get spammed with hundreds of messages. It would be possible to add some message after the bot has caught up, but be aware that all repo subscribers will see them.

Checklist

• All authors have signed the CLA at https://cla.js.foundation/jquery/jquery
• New tests have been added to show the fix or feature works
• Grunt build and unit tests pass locally with these changes
• If needed, a docs issue/PR was created at https://github.com/jquery/api.jquery.com

[timmywil]

Good idea!

[timmywil]

@dmethvin Please merge at your convenience.