Allow specifying which commentaries to return when calling `texts/:ref?commentary=1`

[M-Zuber]

The list of commentaries that is returned can be exceptionally large, and often the use case for the api consumer is limited to a small subset. It would be convenient to be able to specify a subset of commentaries.

For example, if I want to use the api to get todays Aliyah for Shnayim Mikrah with Rashi, I have to make 3 calls https://www.sefaria.org/api/texts/Genesis.28.10-22?context=0 https://www.sefaria.org/api/texts/Onkelos_Genesis.28.10-22?context=0 https://www.sefaria.org/api/texts/Rashi_on_Genesis.28.10-22?context=0 and reduce the results into a single array.

[nsantacruz]

This is a great idea for a pull request. I agree that this is an issue but it is low priority for us since there is a workaround and it is not a bug in our site. The API is defined here: https://github.com/Sefaria/Sefaria-Project/blob/master/reader/views.py#L1204 Feel free to post comments if you have questions on the code.

[M-Zuber]

I would have to learn Python first so if someone wants to go first, please feel free

[nhw80697]

זה אמנם לא באג, אבל זה שיפור נחוץ מאוד לפחות לחלק את הפרשנים ל'ראשונים' ו'אחרונים' אני לא צריך למשוך אלפי פרשנים כשאני צריך בסך הכל רש"י ורמב"ן