Create a new version on conflict when the user selects "Choose local"

When a conflict arise, the user can choose between keeping the remote document or the local one. If the local one is selected, then the remote one is "lost" for everyone.

Think about this scenario:

• UserA, UserB and UserC synced the same file.
• They both stopped their Drive and made modifications on that file.
• When they start Drive again, there are conflicts.

If UserA chooses to keep its version, then UserB and UserC will lost their version.
There is/are several possible issues there depending of the concurrency of actions and choices done, but the idea is to never lost anything.

So, when UserA selects "Choose local", then a new version of the document should be created (via the Document.CreateVersion operation) and then the local file can replace remote one.

Ultimately, in our scenario, the same document will have 3 new versions and even if everyone will have the same version at the end, each user can then get back its changes by browsing differents versions of the document on the browser.

Feature

This is considered a new feature and so a new "features parameter" will be created, enabled by default: conflict-versioning.