Use document user change token for WOPI file version

The blob digest is currently used for the WOPI file version. However, the WOPI documentation states:

This value must change when the file changes, and version values must never repeat for a given file.

The file version value will change if the blob is updated, but if an old blob is set back, the value will repeat.

Using the document user change token should fix the issue as the value won't repeat for a given document.

The user change token is updated when Office Online calls the PutFile operation.

Update both:

• the Version value CheckFileInfo endpoint
• the X-WOPI-ItemVersion header returned by the PutFile endpoint

This change could be tested on
https://nuxeo-test-wopi-demo.platform.dev.nuxeo.com/nuxeo/
https://nuxeo-prod-wopi-demo.platform.dev.nuxeo.com/nuxeo/