[New feature] full code pickle for arbitrary modules

[crusaderky]

As described in cloudpipe/cloudpickle#206

[jcrist]

This has been added in cloudpipe/cloudpickle#417, and works fine with distributed & dask. I don't think there's anything we need to do on the dask side? Closing, feel free to reopen if more work is needed.

[crusaderky]

cloudpickle now supports the feature, but distributed.protocol.pickle offers no way to disable pickle.
Functions imported from a module that exists locally but don't exist remotely will be successfully serialized with pickle on the client, but fail to deserialize on the workers.

As described in cloudpipe/cloudpickle#206, dask needs to offer a switch to completely bypass pickle or cloudpipe/cloudpickle#417 won't have a chance to run.

[ian-r-rose]

This already works today cf #6466

[crusaderky]

Thanks for the clarification @ian-r-rose , I was not aware