This is a proposal to add schema, timestamps and unique ids to
events. For now just JS ones but I propose to do these for all
events the server sends that might be end user consumed.
These exist to help the user identify a message even if it was
sent to a 3rd party system, the schema will be translatable to
a well known url like https://nats.io/schames/jetstream/event/v1/obs_ack.json
or to another wll known identifier like a NATS subject name
We'd publish JSON schema documents at these well known locations
describing each key and so forth
