Option for publisher to only emit events sent over the Ably network

At the moment, the locations SharedFlow on the publisher is emitted to for any enhanced location update received by Mapbox, regardless of whether or not it was sent to subscribers over the Ably network. This can make testing problematic when we're comparing what the publisher sends and the subscriber receives. Customers listening may also only want to be notified of updates that have been sent out.

We could therefore make a way in which the publisher only emits events that have been sent over the Ably network, such as:

Having a separate flow with a contract that events are only emitted once we know they're on the Ably network
Adding a builder option that would change the behaviour of the existing locations slow to achieve the same effect

Original conversation: https://ably-real-time.slack.com/archives/C01EPJENRD0/p1673630012583289

ably / ably-asset-tracking-android

Option for publisher to only emit events sent over the Ably network #913