benchmark commit step and ark counterparts
this MR adds a benchmark for
- the KZG10 trusted setup creating of
ark-poly-commit
- the KZG10 commit of
ark-poly-commit
- our own implement of the commit in
zk::commit
there is also a slight improvement to the previous benchmarking of our zk::setup
: the degree of the trusted setup is now computed once and for all before the benchmarking loop starts, because it's not what is of interest, let's not benchmark it.