Introduce default wp-cli.yml for core development

[westonruter]

When working in the develop repos, and at the repo root, you have to invoke WP-CLI with the --path=src/ parameter, unless you cd into the src (or build) directory first. It would be nice if a default wp-cli.yml file were included in the root so that any WP-CLI commands would default to the install in the src directory.

[jorbin]

I really like this idea. It's simple and will make a tool that is aligned with core more usable. Let's do it!

[wonderboymusic]

In 28221:

Introduce default wp-cli.yml for core development.

Props westonruter.
Fixes #28036.

[nacin]

weston mentioned this to me at WordCamp Austin. 100% for it.

[jonathanbardo]

Thanks weston! This is awesome.