Remove redundancy of filter and score functions in scoring notebook

[ibludau]

Is your feature request related to a problem? Please describe.
filter_with_xx functions in the scoring notebook are redundant and should be revised.

Describe the solution you'd like
Use a single combined function for 'filter_with_xxx' and 'score_xxx'.

Describe alternatives you've considered
Call 'filter_with_xxx' within 'score_xxx'.

Additional context
The 'filter_with_xxx' functions were introduced with commit: eee2972 >> 3 Aug 2020
Here, an unused 'fdr_level' parameter was additionally added.

[jalew188]

In fasta.py,

def get_frag_dict(parsed_pep, mass_dict):
    frag_dict = {}
    frag_masses, frag_type = get_fragmass(parsed_pep, constants.mass_dict)
    ...

the mass_dict argument is never used as well.