Allow PUT Event Metadata such that fields like people_count can be recorded for every event (by a logic module in that room)

[w-le]

Allow PUT Event Metadata such that fields like people_count can be recorded for every event (by a logic module in that room, as the event is occurring in the room).

As discussed with Steve, Will, Alex.
This will allow a much easier alternative to Concierge reports page querying Influx directly and having to collate data between staff-api and influx.

Bonus: record min, max, avg people counts for every Event.
Maybe something like:

event.ext_data.people_count: {
min: 2
max: 3
avg: 2.86
}
Primary Goal:

Frontend apps querying events in a date range, should receive people count data if it's been added to event metadata (by a logic driver, during event start-end time)