expose telemetry #123
Description
currently, the state of the system can be introspected (Journey.Tools.summarize/1, Journey.Insights.Status.status/1, etc.), but the package should also expose reasonable telemetry.
as part of this workitem, define metrics/counters to be exposes, and implement the exposing. ; )
some good examples:
https://hexdocs.pm/phoenix/telemetry.html
https://hexdocs.pm/ecto/Ecto.Repo.html#module-telemetry-events