[turbopack] vibecode a benchmark runner for module-cost (#82287)
# Add automated benchmark runner for module-cost
## What?
This PR adds an automated benchmark runner for the module-cost benchmark, allowing for consistent measurement of module loading and execution times.
## Why?
It is to tedious and error prone to run the benchmark.
## Usage
Build `next` and turbopack however you like
```
pnpm i
pnpm prepare-bench
pnpm build-webpack (or build-turbopack)
pnpm benchmark
```
## How?
v0 mostly