Images for plugins in production mode result in 404s
Images are going through the legacy asset helpers in sprockets-rails, we need to fix that.
For plugins we need to ensure that the digest is looking up digested assets in production and ensure that the prefix is set in order to generate the proper path for the assets.
This will allow the use of image-url in sass for the correct retrieval of digested images.
Fixes #14645: fix production images for plugins.
Images were going through the legacy asset helpers in
sprockets-rails, this commit sets some options on the context
class to ensure we are looking up digested images in the correct
(cherry picked from commit db8510329fc284bd17cea01df09ea0a5f4f5364b)