examples: Add Push to grafana alloy example

[Rperry2174]

We recently added support for pushing to grafana alloy. We shoudl create an example here which shows how to push to Grafana alloy as an "in-between" before sending the data to the backend.

1. we should copy our golang-push/rideshare example and add grafana alloy to it
2. We should leave placeholders to show how one would centralize their authentication information on grafana alloy instead of in the sdk
3. We should replace the readme with one that explains why we built this feature

cc @marcsanmi