Add PyTypeMethods trait with qualname method

[LilyAcorn]

This allows calling Bound<'py, PyType>::qualname().

[codspeed-hq]

CodSpeed Performance Report

Merging #3854 will degrade performances by 16.65%

_{Comparing LilyFoote:qualname-bound (291145f) with main (c33d330)}

🎉 Hooray! codspeed-rust just leveled up to 2.3.3!

A heads-up, this is a breaking change and it might affect your current performance baseline a bit. But here's the exciting part - it's packed with new, cool features and promises improved result stability 🥳!
Curious about what's new? Visit our releases page to delve into all the awesome details about this new version.

Summary

❌ 3 regressions
✅ 76 untouched benchmarks

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

Benchmarks breakdown

	Benchmark	main	LilyFoote:qualname-bound	Change
❌	extract_float_downcast_success	425.6 ns	508.9 ns	-16.38%
❌	extract_float_extract_success	417.2 ns	500.6 ns	-16.65%
❌	sequence_from_tuple	232.8 ns	260.6 ns	-10.66%

[LilyAcorn]

Ah! I just had another look at #3853 and I think that covers this.

[davidhewitt]

Maybe you meant #3705 ?

[LilyAcorn]

Oops! Yes I did!