Simulate arrival of finality certificate from future rounds

[masih]

In a realistic environment it is possible for finality certificate from future rounds to arrive at any time with un-guaranteed delivery semantics. Enhance simulation options such that the following is configurable:

• arrival of finality certificate from future instances for all participants
• asynchronous skip ahead to a future instance among participants
• partial delivery of finality certificate and therefore uneven skip ahead to future round across the network

[Stebalien]

This is now somewhat tested in TestPauseResumeCatchup, but better simulation tests would be nice.

[rjan90]

Are we testing security or performance with this?

[Stebalien]

Correctness.