Implement ACP-118 Package

[joshua-kim]

Why this should be merged

Implements p2p client + server logic for signature request handling as described in acp-118 (ref).

How this works

Client:

• Introduces an aggregator type which will make signature requests in batches block until a caller-provided threshold of stake signs the provided warp message
• Introduces a server handler that servers aggregation requests

How this was tested

• Added unit tests