Ballista: Implement configuration mechanism

[andygrove]

Is your feature request related to a problem or challenge? Please describe what you are trying to do. There is currently no way to specify configuration parameters such as default partition count in Ballista.

Describe the solution you'd like As a user, I would like to be able to set configurations such as default partition count and have these settings propagated to the scheduler and executors via protobuf.

Describe alternatives you've considered None

Additional context None