feat(batch/simple): add a simple cloud batch example

[alevenberg]

Is this the first example in a series? Because we have examples like this, the difficult bit is "How do I run my C++ program in Cloud Batch?"

Yes, this would be the first.

I'm thinking:

1. Run a .json easily
2. Run a C++ application (includes creating a docker image, uploading it to Artifact registry, and maybe doing something once the job finishes)
3. Run a embarrassingly parallel app
4. Run something with MPI