Add an option to filter rules

[versae]

In some cases it might become handy to filter out some of the rules, e.g., ignoring prefixes, hence the need to add that option.

It could be in the form of a filter function, such as rules_exclude, or a parameter based on rule["kind"], so rules_kind could be either AFFIXES_PREFIX or AFFIXES_SUFFIX and filter out appropriately.

Right now the only way to achieve this is by loading the rules, doing the filtering, and passing the resulting filtered list to the AffixesMatcher constructor.

from spacy_affixes.utils import AFFIXES_SUFFIX, load_affixes                                                                                                                              

# Let's ignore all prefix rules
suffixes = {k: v for k, v in load_affixes().items()
                 if k.startswith(AFFIXES_SUFFIX)}                                                                                                                      
affixes_matcher = AffixesMatcher(nlp, split_on=["VERB"], rules=suffixes) 

Maybe both options would be good to have.