* Always include the content hash in the cache key for unprocessed images.
* Always include the image config hash in the cache key.
This is also a major cleanup/simplification of the implementation in this area.
Note that this, unfortunately, forces new hashes/filenames for generated images.
Fixes#13273Fixes#13272
This commit pulls most of the image related logic into its own package, to make it easier to reason about and extend.
This is also a rewrite of the transformation logic used in Hugo Pipes, mostly to allow constructs like the one below:
{{ ($myimg | fingerprint ).Width }}
Fixes#5903Fixes#6234Fixes#6266
