Be able to set the state of an object to previous state in version control

[yaustar]

Dependent on https://github.com/playcanvas/editor/issues/135

Users want to be able to 'restore' an object's state to a previous version

[vmwxiong]

Bumping this to mention that we have a very frequently used template that we use to configure data for each of our stages. Designers create dozens of instances of this template for each stage, and change the values of each one. Everyone is aware that you should never apply changes to this template, but multiple times we've had designers accidentally hit apply, and essentially need to scrap all of their work since their last checkpoint as a result.

This feature would make things way easier to recover from if we could just revert the template in question. Thanks!