Regenerate webp format

[strarsis]

Feature Request

wp CLI media regenerate should also generate the webp format for thumbnails of already uploaded images.
WordPress 5.8 added native webp format support.
Currently media regenerate regenerates the thumbnails only in jpeg/png format, but doesn't also output them in webp format.

Is your feature request directly related to a specific, existing command?
wp media
wp media regenerate

Is your feature request about a new command, or a more general idea?
The existing media regenerate should be extended so that it can handle a very often occurring case (regenerating webp format from already uploaded media images).

• Yes, I reviewed the contribution guidelines.

Describe your use case and the problem you are facing
Use case: Existing WordPress sites with existing, already uploaded media prior to WordPress natively supporting the webp format.
Problem: wp media regenerate currently doesn't regenerate thumbnails (of already uploaded images) for the webp format.

Describe the solution you'd like
Some hook/trigger/code inside media regenerate so webp format is also generated for thumbnails.

[swissspidy]

If a plugin configured WebP conversion, this should be working automatically. But since core doesn't do this out of the box, neither should WP-CLI.