feat: Expose CharacterNgrams extractor for direct use in Python

[RichardOberdieck]

Is your feature request related to a problem? Please describe.
I would like to use a vector database (qdrant in this case) rather than the HashDb from this repo. To make the results reproducible, I therefore need to create the embedding from the CharacterNgrams extractor. Currently, this is not possible.

Describe the solution you'd like
Be able to call the CharacterNgrams extractor directly from Python, e.g.

from simstring_rust.extractors import CharacterNgrams

extractor = CharacterNgrams(2, endmarker='$')
embedding = extractor.apply("Some text")

Describe alternatives you've considered
N/A

Additional context
N/A

[PyDataBlog]

#47 closes this