Unable to scan files that have been uploaded on a different server and don't exist

Problem/Motivation

Development process uses different processes to have production images available to the non-production site. If for some reason the image is expected to be available (eg. an entity was created in production and synchronised back to the non-production environment but this process hasn't synchronised the files back).

Steps to reproduce

1. Create a media entity
2. Remove the image item

Proposed resolution

1. Allow unchecked files to be skipped

User interface changes

- Add configuration option