Wrap or refactor EmergencyBrake

[alcueca]

EmergencyBrake is cumbersome to use and maintain, to the point that it has been mostly neglected since launch.

The EmergencyBrake should be refactored or wrapped, so that the user experience is something like calling isolate(address), instead of remembering with set of arbitrary-looking hashes need to be executed.

I think we can still store a very long calldata string as the plan, indexed by the contract that we understand that we are isolating. We would need to be able to edit the plan, so maybe storing it as an array of calls would work better, not sure.

If we choose to wrap instead, then the wrapper would map one address to a number of plans identified by their hash, and execute them sequentially.

[alcueca]

Done