Ensure time-sensitive message ingestion is reliable

[zone117x]

Some types of events ingested by chainhook now record a date.now() timestamp which is used by clients to track important latency metrics.

It's not clear to me if this is reliable in the threading model used by chainhook. For example, can the event-ingestion component in chainhook be slowed down by other operations in chainhook? It seems like there's a lot of serial/synchronous IO processing (disk read/write, network read/write, etc) which doesn't use async code.