Add rule lower lemmatization

[jademlc]

The special lemmatization will lowercase the whole text, even proper nouns

Description

Added a function to define a special_lemmatization that returns text.lower() even when the token is detected as a proper nouns. This change is useful when using spaCy Matchers with noisy texts containing a lot of uppercases. This was discussed in this issue: explosion#11051
Using the special lemmatizer, the lemma of 'CAT' will be 'cat' instead of 'CAT'.

Types of change

This change is a enhancement of the lemmatizer.

Checklist

• I confirm that I have the right to submit this contribution under the project's MIT license.
• I ran the tests, and all new and existing tests passed.
• My changes don't require a change to the documentation, or if they do, I've added all required information.

[YaYaB]

should be better renaming it rule_lower_lemmatize to have something explicit

[YaYaB]

a lot of duplicate code for only the removing of

  if univ_pos == "propn":
      return [string]
  else:

I would copy paste the rule_lemmatizer to __rule_lemmatizer_ private class with a lower argument.

# __ as prefix to define it as private
def __rule_lemmatizer__(self, token: Token, tolower: boolean = False):
...
...
if not tolower and univ_pos == "propn":
    return [string]
else:
    return [string.lower()]
...
...

and then create

def rule_lemmatize(self, token: Token) -> List[str]:
        """Lemmatize using a rule-based approach.
        token (Token): The token to lemmatize.
        RETURNS (list): The available lemmas for the string.
        DOCS: https://spacy.io/api/lemmatizer#rule_lemmatize
        """
    self.__rule_lemmatize__(token)
    
def rule_lower_lemmatize(self, token: Token) -> List[str]:
        """Lemmatize using a special approach that lowercases the whole text
        token (Token): The token to lemmatize.
        RETURNS (list): The available lemmas for the string.
        DOCS: https://spacy.io/api/lemmatizer#rule_lower_lemmatize
        """
    self.__rule_lemmatize__(token, tolower=True)

[YaYaB]

elif self.mode == "rule_lower":
    self.lemmatize = self.rule_lower_lemmatize