`artifacts_by_user_v1` dbt mart model

[ryscheng]

What is it?

This should be modeled similarly to artifacts_by_project_v1 with the following columns:

• artifact_id
• artifact_source_id
• artifact_source
• artifact_namespace
• artifact_name
• user_id
• user_source_id
• user_source
• user_namespace
• user_name

This should map any artifacts owned by users (e.g. GitHub users, EOA addresses, etc)