Major changes includes:
1. Add a new FDB role responsible- EncyrptKeyProxy. The role is
responsible to expose APIs to fetch encyrption keys interacting
with external Encryption KeyManager interface.
2. The process is a FDB singleton process following similar recruitment
rules as other singleton processes in the system.
3. Code to recruit the worker process; given the encryption keys are
needed during recovery (decode TLog records), for now the process
is co-located in same datacenter as ClusterController.
4. Skeleton process actor code; more functionality will be added in
subsequent PRs.
NOTE: The code is protected under a SERVER_KNOB with the default
value as 'false' for now.
A.J. Beamon