resources: Fix 2 image file cache key issues

* 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 #13273
Fixes #13272

resources/resource.go

@@ -363,6 +363,7 @@ type genericResource struct {
 	sd    ResourceSourceDescriptor
 	paths internal.ResourcePaths
 
+	includeHashInKey     bool
 	sourceFilenameIsHash bool
 
 	h *resourceHash // A hash of the source content. Is only calculated in caching situations.
@@ -452,6 +453,10 @@ func (l *genericResource) Key() string {
 		if l.spec.Cfg.IsMultihost() {
 			l.key = l.spec.Lang() + l.key
 		}
+
+		if l.includeHashInKey && !l.sourceFilenameIsHash {
+			l.key += fmt.Sprintf("_%d", l.hash())
+		}
 	})
 
 	return l.key