Add check to skip HTTP fetch for non-HTTP URLs in processImageField(),
matching the existing behavior in setPerformerImage() and setStudioImage().
This allows scrapers to return base64 data URIs (e.g.,
`data:image/jpeg;base64,...`) directly without triggering an HTTP fetch
error. Previously, processImageField() would attempt to create an HTTP
request with the data URI as the URL, causing "Could not set image using
URL" warnings.
c0260781a5