GMS: view installation via 2PC

Investigate whether view installation should optionally be done via 2PC. Example:

• View is A,B,C,D, splits into A,B and C,D
• Before AB is installed in A and B, view A,B,C is installed
  • (C hasn't been suspected yet. This can happen with FD)

Infinispan's rebalancing algorithm has problems with this, as it tries to assign state to C which however isn't reachable from the A,B side of the network partition. It would be better if A,B,C,D went directly to A,B and C,D

Investigate whether we should add a property to GMS which defines whether to use 2PC for view installation (default would be false). The algorithm would work as follows:

• Send a PREPARE_VIEW(view) message
• When all responses have been received -> send a COMMIT_VIEW message
• Else
  • Inject SUSPECT(C) event for all misisng acks OR
  • Set a timer to go off in N ms -> when it fires, send the COMMIT_VIEW msg
  • If another view is installed before the tmer goes off (e.g. A,B) -> kill the timer