Allow tokens in Watermark Image URL

Problem/Motivation

I'm trying to create an image effect that combines multiple image files from a node into a single collage. One idea was to use a node image field token like [node:field_image:0:entity:url] in the watermark image field so that I could build the collage as an image style. However, the site checks to see if it's a valid url and it fails.

I could also see this feature be helpful to build images with logo watermarks that were defined in another node field (like can be done with text but using image references)

Proposed resolution

Process tokens in file paths like Watermark and possibly others (background), and ignore in file validation if it contains a token.