The promise message should include the last accepted proposal

[meteam2022]

Describe the Bug

When an Acceptor receives a prepare msg, it replies with a promise msg which should include the last accepted proposal it has received.
When a proposer receives majority promise msgs, it should set the value to the value in the last accepted proposal with highest proposal number. If all last accepted proposals are null, it can set the value to its originally proposed value.

However, the current code doesn't include the last accepted proposal:

paxos-rs/src/main.rs

Lines 114 to 115 in 3679111

	let msg = RegisterMsg::Internal(PaxosMsg::Promise(
	request_id, org_sender, rid,

To Reproduce

Below is an error trace. The server plays both Proposer and Acceptor role, but it does not send a Prepare msg to itself, it might be another bug.

If we separate the Proposer and Acceptor role, the bug trace helps us better understand the issue:

[isubasinghe]

Thanks a lot for your report @meteam2022, I will fix this when I get some free time.