Report to Odoo16 instead of intermediate postgresql

[HappyTetrahedron]

Summary

This replaces the transformation process: instead of creating interim results to be stored in Postgres, we now create metered billing records that are sent directly to Odoo16. Invoicing is no longer managed by this component.

This is a breaking change. The system is fundamentally reworked.

Checklist

• [x] Categorize the PR by setting a good title and adding one of the labels: bug, enhancement, documentation, change, breaking, dependency as they show up in the changelog
• [x] Update tests.

[HappyTetrahedron]

Superseded by https://github.com/appuio/appuio-reporting/pull/3