## Summary
- Adds a new `upgrade:1-21:backfill-datasource-to-workspace` command
that copies `dataSource.schema` into `workspace.databaseSchema` for all
active/suspended workspaces that haven't been migrated yet
- Registers the command in the 1-21 upgrade module and wires it into the
upgrade runner (runs before other 1-21 commands)
- Part of the ongoing deprecation of the `dataSource` table in favor of
storing `databaseSchema` directly on `WorkspaceEntity`
