Publish benchmark crate so that it can be used as a library in Ballista

[andygrove]

Is your feature request related to a problem or challenge? Please describe what you are trying to do.
I am starting to get frustrated with maintaining two copies of the same benchmark 😩

Describe the solution you'd like
Publish datafusion-benchmark crate so that Ballista can use it as a depedency

Describe alternatives you've considered
None

Additional context
None