compute: factor out command type

Created by: rvantonder

TL;DR, better types.

After building out some functions I realized the types don't quite match up to the logic separation I want. Having parameters be tagged along across all variants of the previous Query type is a sign that the type is too broad, and I already ran into this issue with tests, where parameters didn't matter and is implicitly nil. This PR factors out the Command part of a compute query (which we want for the sum types) and parameter part which is always part of the Query.