Expand benchmark coverage

[jlhcrawford]

Expand overall coverage of native benchmarks. Benchmarks added include

• BFV Negate
• CKKS Negate
• BFV Ctxt - Ctxt subtraction
• BFV Ctxt - Ptxt subtraction
• CKKS Ctxt - Ctxt subtraction
• CKKS Ctxt - Ptxt subtraction
• High level forward and inverse NTT
• Low level forward and inverse NTT (direct call to ntt_negacyclic_harvey and inverse_ntt_negacyclic_harvey)

[WeiDaiWD]

Thanks for adding these. There is one issue though. There is another pair of low level forward and inverse NTT, *_ntt_negacyclic_harvey_lazy, which are faster. Could you please add those two as well?

[jlhcrawford]

Thanks for adding these. There is one issue though. There is another pair of low level forward and inverse NTT, *_ntt_negacyclic_harvey_lazy, which are faster. Could you please add those two as well?

I've added benchmarks for *ntt_negacyclic_harvey_lazy called *NTTLowLevelLazy. Feel free to change the names of course.