pypi: Schedule ingestion

Once everything is developed, packaged, puppetized, trigger the ingestion:

• scheduler updates (manifest, scheduler task type)
• pypi lister (manifest, lister-pypi db)
• pypi loader (manifest)
• swh-workers: Deploy swh-loader-pypi service
• saatchi: Deploy scheduler update
• scheduler: Add task_type origin-update-pypi
• Add scheduler task for listing pypi (and let the magic happen)

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Migrated from T1181 (view on Phabricator)