[Sample] add a sample for multiple outputs

[hongye-sun]

Add a basic sample to demonstrate returning multiple outputs from a single step. It seems that all samples today are have only single output.

[Ark-kun]

The Lightweight components sample has multiple outputs https://github.com/kubeflow/pipelines/blob/master/samples/notebooks/Lightweight%20Python%20components%20-%20basics.ipynb

But I agree that we need more components and samples demonstrating that.

What do you think about just making a component like Split lines that can for example split table into train/test.

[Ark-kun]

Can you look at the Lightweight sample? WDYT?

[zanedurante]

For me, the lightweight sample is alright -- I only found it by first finding this GitHub issue though.
Is there a way to do this using compiler.build_python_component() for non lightweight components? I am following the example but I am getting Output type not supported and supported types are [int, float, str, bool] (using compiler.build_python_component()). It works if I use func_to_container_op().

[zanedurante]

This issue has been documented here: #1580

[jessiezcc]

/area samples

[gaoning777]

I'm including this as part of the sample efforts.