Done to circumvent criterion limitation regarding automatic
truncation of long benchmark ID.
Using a println() call we ensure the complete name is displayed
before benchmark execution to ease manual parsing and debugging.
It seems that in
```rust
bench_group.bench_function(&bench_id, |b| {
// some code
b.iter(|| {
// function to bench
})
});
```
If we put code in the '// some code' part, it affects the measurements
the slower this code is the worse the measurements can be.
For many operations the gap is small (a few ms or no gap),
but for the division the gap was around 500ms.
So to reduce this, we move out what we can, moving
the keycache access is the most important aspect as it
cost around 70ms to 100ms.
A LazyCell is used in order only access the keycache is the bench is not
filtered out. Which is the behaviour we had before this commit, and the
behaviour we want to keep so that running specific benches via regex
selection stay fast.
Also, for clean input benches, we use `iter` instead of `iter_batched`
as it makes more sense and should give more accurate results as
iter_batched timing include other things that just the timing of the
function.
