Refactor event struct for clarity

[ericvolp12]

This change updates the event struct to be more human-readable now that we support compression and don't need to save characters as greedily.

Motivation behind this change is to make the event stream readable for someone without having to go lookup docs on event structure. Some existing fields have been a bit cryptic with naming and with value abbreviations, making the stream less understandable to new developers.

Deprecated fields:

• event.type -> event.kind
  • com, id, acc -> commit, identity, account
• commit.type -> commit.operation
  • c, u, d -> create, update, delete

To support backwards compatibility for a brief window, the old fields and values will still be emitted during a migration window.

[bnewbold]

great! glad that we found a migration path. and additionally I like that there are now different words for the overall event and commit "type"; and that the field "type" won't be used in commit operations (they could be redundant/confusing with $type for records, which is what is in the collection field)

[mackuba]

Btw, regarding compression - are other more classic compression types like gzip or something available too, which don't require a custom dictionary and might be supported more natively by a websocket library? (I don't know if this is a thing in general in websockets)

[bnewbold]

@mackuba I don't think there is too much gain compressing individual messages with something like gzip: the messages are too short for compression to work well. in theory stream compression might work, but that doesn't fit well with the current jetstream architecture. I would recommend just disabling compression.