Profile and improve runtime

[bittremieux]

Profile runtime to identify bottlenecks and improve speed by optimally parallelizing as many parts of the code as possible.

• [ ] Parallelize multiple peak file reading #26.
• [ ] Parallelize spectrum preprocessing.
• [ ] Parallelize spectrum similarity calculations.
• [ ] Parallelize rescoring feature calculations.
• [ ] Use a GPU-powered ML model for rescoring.