[EPIC] Expand CUB APIs for user-specified algorithmic properties

[jrhemstad]

Requirements API

• Initial investigation into API design for user-specified determinism guarantees in Thrust and PSTL #1187

User-defined Tuning API

• Investigate productizing tuning infrastructure to allow users to find optimal tuning for their use case

[gonidelis]

Should we close this in favor of #5635 ?