refactor: reduce memory usage of comparing alignments

[balajtimate]

Is your feature request related to a problem? Please describe.
Currently, the _align_mates function in get_library_type.py uses a lot of memory to store the alignments from both input samples and compare them to find concordant mates.

Describe the solution you'd like
Implement a memory-efficient solution to compare alignments on the fly without the need to actually store both alignments in memory.