#926 datashard 0.11 on S3 with offline table migration

EARS SPEC: - The logger shall store tables on S3 using datashard>=0.11. - Every existing production table shall be migrated with datashard migrate while workers are stopped, after a backup. - When a workflow runs, its logs shall be retrievable through the logs API from S3. Parent epic: #913. Synthesis (technical problems / solution domains / alternatives) recorded as a comment when started.