Fix incorrect chain selection

[gamcil]

• Go back to getting query chain name from query name in beforeMount()
• Use query chain selection when mapping 1-based residue numbers in alignment to residues in corresponding chain e.g. 1NUN chain B residues go from 151-359, but alignment reported as 1-205, so select chain B and map 1->151, 2->152, etc

[gamcil]

Should fix weirdness in https://search.foldseek.com/result/amsElCipotsqxX1-TO9SDNnQpXsRZPhhnRGg6Q/1