Add wallclock benchmarks

Problem

CodSpeed is good, but has some anomalies.

In particular:

1. All system calls (e.g. system allocator) are "free" on Codspeed's measures.
2. They say it doesn't take into account the branch predictor.

Mispredicted branches can be a significant perf hit, which we're failing to measure. In particular, I have some ideas to replace branching in lexer with straight-line code (https://github.com/oxc-project/backlog/issues/108). I suspect this could be a significant gain, but it won't register on current CodSpeed benchmarks - so we can't evaluate this at present.

Possible solution

Introduce wallclock benchmarks (not run with Valgrind) in addition to the existing benchmarks.

How?

Can use the same hack I wrote to run NAPI benchmarks as normal wallclock benchmarks and get the results into CodSpeed.

An improvement would be if it's possible to synthesize fake .out files to send to CodSpeed.

Start by examining the existing hack used to run NAPI benchmarks as normal wallclock benchmarks and how current CodSpeed benchmarks produce results. Determine whether wallclock runs can be integrated directly or require synthetic .out files. Done means wallclock benchmarks run outside Valgrind and their results reach CodSpeed alongside the existing measurements.