This CR makes raft-facing logic more contained by encapsulating
them in a seperate object, in a new file. This CR also simplify
the implementation by removing some unecessary locking and channels

Change-Id: Ibefe74a35f0645955cbb3885efc8a3f8aaa0a8ca
Signed-off-by: Jay Guo <guojiannan1101@gmail.com>