Feature Proposal: Include book metadata in EPUB export
This ticket stems from #254, which is being broken out into more granular development tickets to make prioritizing the next development steps easier.
The metadata from the book interface should be included in the exported EPUB. There are two steps to this:
- Metadata from the book metadata interface should always be included in any HTML that Editoria exports, for export to any format.
- The PS EPUB component should be updated to parse and repackage the metadata in the HTML into metadata to be included in the EPUB.