feature: create message tracking service using SDK

[luketchang]

Want a tool that picks up Dispatches and tracks the lifecycle of a message. If the message is stuck at a given stage for too long (Update, Relay, Process), we want to send an alert in Slack.

Structure:

• Initially starting at latest block, pick up Dispatch events and store them in array or mapping
• For each stored Dispatch event, create a NomadMessage object and continuously poll for events
• If the NomadMessage status is stuck at one stage for longer than expected, send Slack alert with origin chain, dispatch tx hash, and stuck stage
• If a NomadMessage reaches the Process status (complete), delete from array

[yourbuddyconner]

Note: This issue is for an MVP tool to ship immediately to give us insight into channel stalls. We'll then fast-follow with a refactor shortly that incorporates this into a new and improved nomad-monitor package.

[luketchang]

Yeah I think this can go in nomad-monitor and then we will refactor the rest of the package after