Exclude MacOS "Icon\r" files from deposits

[andrewjbtw]

We should exclude MacOS Icon\r files from deposits, just like we exclude .DS_Store files. These files cause a number of problems:

• they have a control character \r (carriage return) in the name, which causes issues with parsing checksum manifests (see: https://github.com/sul-dlss/preservation_robots/issues/540 )
• they use MacOS filesystem resource forks and so do not copy properly to non-Mac systems
• probably because of the resource fork issue, they appear to end up as empty files when copied to a Linux filesystem
• they clutter the file list on the Purl/sul-embed

(For more background, I found some info here.)

Excluding these files won't affect the data people and will make our lives easier, as we spent a considerable amount of time recently trying to get a deposit accessioned that came with Icon\r files.