* Clickhouse migration: add ingest_counters table

* Configure ingest counters per MIX_ENV

* Emit telemetry for ingest events with rich metadata

* Allow building Request.t() with fake now() - for testing purposes

* Use clickhousex branch where session_id is assigned to each connection

* Add helper function for getting site id via cache

* Add Ecto schema for `ingest_counters` table

* Implement metrics buffer

* Implement buffering handler for `Plausible.Ingestion.Event` telemetry

* Implement periodic metrics aggregation

* Update counters docs

* Add toStartOfMinute() to ordering key

* Reset the sync connection state in `after` clause

* Flush counters on app termination

* Use separate Repo with async settings enabled at config level

* Switch to clickhouse_settings repo root config key

* Add AsyncInsertRepo module