test(instance_test.go) add tests to cover prepare-reply helpers
test(instance_test.go) add tests to cover prepare-reply helpers

add TestUpdateReocveryInstance
add TestHandleCommittedPrepareReply
add TestHandleAcceptedPrepareReply
add TestHandlePreAcceptedPrepareReply

go-distributed/epaxos,sargun/epaxos,go-distributed/epaxos,sargun/epaxos