libreoffice-online/wsd/wopi

This directory holds WOPI-specific code.

First and foremost, it is to isolate it from Mobile Apps
that do not have any dependencies on WOPI. This will also
enable stubbing out the same classes/functions for Mobile
Apps, so we wouldn't need so many compile-time directives
to exclude such code.

This also helps reduce the size of the translation-units
where previously this code resided, making them more
manageable in size and complexity.