* Parse event URL in Plausible.Ingestion.Request

* Parse event domain in Plausible.Ingestion.Request

* Rework ingestion pipeline processing (#2462)

* Rework ingestion pipeline processing

So that Request can have multiple domains and
based on that each event is processed uniformly.
The build_and_buffer/1 function now returns an
accumulator with all the dropped/buffered events
for further inspection.

* Reduce function complexity

* Don't chain struct fields to check for an empty host

* Separate referrer and utm tags

* Fix up `with` clause, credo was right cc @vinibrsl

Co-authored-by: Adam Rutkowski <hq@mtod.org>