Permit file revisions of galley files and XML

[asmecher]

Submission galleys and JATS XML (#7505) are recorded using the submission_files database table and associated PHP classes. These underlying tools support revision tracking (using the submission_file_revisions table). However, it is not yet possible to add revisions to galleys or JATS XML uploads.

Review and modify the submission galley and JATS XML implementations to permit multiple revisions to be uploaded, in support of better tracking of modifications to these files over time.