test: add benchmark for moffat init

[beckermr]

This PR adds a benchmark on the moffat init function.

[codspeed-hq]

CodSpeed Performance Report

Merging #139 will not alter performance

_{Comparing moffat-init (46b8971) with main (a946ce3)}

Summary

✅ 27 untouched benchmarks
🆕 2 new benchmarks

Benchmarks breakdown

	Benchmark	BASE	HEAD	Change
🆕	test_benchmark_moffat_init[compile]	N/A	183.5 ms	N/A
🆕	test_benchmark_moffat_init[run]	N/A	723.7 µs	N/A