Add compliance unique metrics as Snowplow events

This mirrors the following Redis HLL events that are part of the
redis_hll_counters.compliance.compliance_total_unique_counts_monthly
metric as Snowplow events (a mirrored version of g_compliance_dashboard
event has already been instrumented):

- i_compliance_credential_inventory
- i_compliance_audit_events
- g_compliance_audit_events
- a_compliance_audit_events_api

The Snowplow events are complete with a custom context for Redis metrics
migrated to Snowplow events.