Description of the need

I would like to propose for discussion that we allow the image style urls to be altered (hook_image_style_url_alter). My specific use case is to change the extension of an image style conversion so that the filename being served matches the actual format of the image. Currently we have a convert action in Image Effects > Coloractions, but it can't modify the filename so it may be serving a JPG with a PNG extension, or a WEBP with a JPG extension, etc.

GitHub Issue #: 
5745