BACKLOG-3619 - Solve war overlay issue with document-viewer and document-viewer-ee modules
https://jira.jahia.org/browse/BACKLOG-3619

Convert document management modules to OSGi bundles.
Make document-viewer and document-viewer-ee independent (extracted document-viewer-service part).
Use OSGi services to inject implementations of document viewer, document thumbnails and video thumbnails services into the DM API bean (DocumentManagement).