Out-of-order events are skipped when using the `:concurrency` option

[jdav-dev]

Commanded.Projections.Ecto passes the :concurrency option introduced in commanded/commanded#486 through to the underlying Commanded.Event.Handler. However, out-of-order events are skipped when compared to the projection_versions table.

[slashdotdash]

You must not use the concurrency option with an Ecto projector as it expects events to be processed sequentially and in order.

If the concurrency option is specified for an Ecto projector then a compiler or runtime warning should be emitted as this behaviour is unsafe. I will add this warning.