Add codspeed<>divan compat layer

[GuillaumeLagrange]

Currently implemented

• Simple bench using #[divan::bench]
• Basic argument handler for divan::bench macro
• Argument generator .with_inputs()

TODO before first release

• Automated tests
• Support for all arguments at least in a non compilation breaking way

[codspeed-hq]

CodSpeed Instrumentation Performance Report

Merging #65 will not alter performance

_{Comparing cod-362-add-a-divan-shim (d525802) with main (a65176f)}

Summary

✅ 54 untouched benchmarks

[art049]

This is pretty cool overall and seem much more simple than for our other integration! let's go 💪

[art049]

We also need to run those new benches in the ci workflow before merging

[codspeed-hq]

CodSpeed Walltime Performance Report

Merging #65 will not alter performance

_{Comparing cod-362-add-a-divan-shim (d525802) with main (a65176f)}

Summary

✅ 1 untouched benchmarks
🆕 1 new benchmarks
⁉️ 1 dropped benchmarks

⚠️ Please fix the performance issues or acknowledge them on CodSpeed.

Benchmarks breakdown

	Benchmark	BASE	HEAD	Change
🆕	fibo_10	N/A	3.6 µs	N/A
⁉️	fibo_100	3.6 µs	N/A	N/A

[art049]

🚀
As discused, can you undo the reformating of the doctest in the divan fork's doctests?