Feature Request: Add support for getting older key values from the topo server

[mattlord]

Feature Description

If you realize that you made a mistake e.g. with the ApplyRoutingRules command, there's no way to effectively revert that change today and go back to the previous value.

You could do this if you were prepared for the possibility and saved the current value before updating it, but if not...

Use Case(s)

I would like to be able to revert a topo server key to a previous version to more easily recover from user mistakes or even system bugs.