Order loading summary of wanted refinements

Follow up list copied verbatim from #374: Probably a few these sections will get btoken into sub-issue sets.

[ ] serialize darks and alerts to some kind of config (TOML, and might get deferred)
- this would provide persistent darks and alerts across pikerd restarts
- we could also consider

[ ] maybe drop all the BrokerdX msgs?
- would be nice to shrink our total msg typeset?
- would this make tracing the clearing engine (which is going to multi-host scale) more difficult though?
[ ] connecting to a daemon-ems that had orders clear within it's currently process lifetime should "replay" those clear events/fills to the client which would enable displaying the (near term) historical trades without loading from pps.toml?
- it might make more sense to just support loading from ledgers/pps.toml directly instead of this pseudo optimization?

[ ] how are we going to handle arbitrary such state updates from say, other EMS (clusters) for the purposes of multi-player, and what should be permission system ack in terms of msg fields? deferred to https://github.com/pikers/piker/issues/382
- right now Status.src: str is a "tag" field but likely we'll want to develop this further.

[ ] reloaded lines are highlighted (as though moused over) on client connect not sure if we want this?
[ ] "nav indicators" for any open orders that are "out of view" much like we for pp lines which includes some kinda obvious UX for showing all oipen submissions in summary:
- maybe red, green, and yellow markers each with a count int subscript?
- a hot key e what shows "everything" meaning the y-range jumps to showing all orders + a small margin on in screen

pikers / piker