search: lucky search does not depend on jobutil

Created by: rvantonder

I want to move lucky search out of jobutil (it's getting big). See next PR. But will hit a recursive dependency when:

• jobutil -> calls new lucky package
• lucky package -> calls jobutil.NewBasicJob

The lucky job uniquely has this problem (compared to other jobs) because it needs to call NewBasicJob because it constructs jobs on-the-fly. The solution I'm happy with is to pass it a function to create jobs. This function also replaces the need to pass inputs directly.

Test plan

Semantics-preserving.