snowplow: Ensure all currently used/supported enrichments are implemented & tested

Todo(s):

• ability to provide/parse enrichment configurations

Hardcoded enrichments

• schema field enrichments
• page URI enrichments

Explicitly enabled enrichments from https://ops.gitlab.net/gitlab-com/gl-infra/config-mgmt/-/blob/main/environments/aws-snowplow-prd/templates/enricher-user-data.sh?ref_type=heads

• ip_lookups enrichment
• user_agent_utils enrichment

Resources:

• hard-coded enrichments
• available enrichments
• upstream codebase