Add option to present JATS with galleys

[asmecher]

Starting with OJS 3.6, #7505 adds support for a basic JATS view for editors, supporting both uploaded and generated (JATS Template) JATS documents. However, this is only available to editors and cannot be provided to end users (unless e.g. the document is also uploaded as a galley).

Add support for a mode of operation where the JATS document is made available for view/download by end users.