Release v21.9.1

Fixed

• Start a Development application that uses a Chronicle command response value. Arc's discovered extension points were resolved from the root service provider, so a handler depending on the scoped IEventLog could not be created once the host turned scope validation on, and every such command threw. (#2505)
• Resolve command filters, command execution scopes and query filters from the scope the work runs in, so an implementation of any of these that depends on a scoped service works instead of throwing in Development. (#2505)