Implement structural superimposition and TM-score

[padix-key]

This PR implements the tm_score() function to compute the TM score on two given protein structures (monomeric or multimeric).

In addition superimpose_structural_homology() takes inspiration from TM-align to find corresponding CA atoms (required as input to tm_score()) and to transform the mobile structure minimizing the TM-score.

[codspeed-hq]

CodSpeed Performance Report

Merging #705 will not alter performance

_{Comparing padix-key:structural-superimpose (803f61b) with main (e76eb24)}

Summary

✅ 47 untouched benchmarks
🆕 4 new benchmarks

Benchmarks breakdown

	Benchmark	main	padix-key:structural-superimpose	Change
🆕	benchmark_superimpose[superimpose]	N/A	2.7 ms	N/A
🆕	benchmark_superimpose[superimpose_homologs]	N/A	101.7 ms	N/A
🆕	benchmark_superimpose[superimpose_structural_homologs]	N/A	41.3 ms	N/A
🆕	benchmark_superimpose[superimpose_without_outliers]	N/A	16.5 ms	N/A