Add sort_order parameter for search api

[mirkolenz]

As discussed in #597, Twitter added the new field sort_order to their search endpoints. This PR is a first attempt to include this new parameter in twarc. In my tests, setting sort_order="relevancy" gave a different ordering of results, thus I think it should work.

One comment on my code: Initially, I wanted to add this new parameter to the command_line_search_options decorator. However, it is also used for the counts endpoint, which does not provide the parameter sort_order. Thus, I included the click option for every relevant function individually.

I am happy to modify my code according to your recommendations 😃

[mirkolenz]

I forgot to mention: I did not yet update the docs and tests as I wanted to wait for feedback on the actual implementation. As soon as that is cleared, I will update them as well.

[SamHames]

Thanks for taking the time to submit a PR. This looks good so far, I've just noted one little added mistake in the docstrings.

It would be great if you could add a test case for the sort parameter as well - maybe just by expanding https://github.com/DocNow/twarc/blob/main/test_twarc2.py#L102 with an additional case for the new parameter? Let me know if you want any help with that.

@igorbrigadir might have some more specific thoughts about how to handle the CLI parameters though.

[SamHames]

Sorry, I missed your comment about adding the tests later - I'm happy to merge and release once there's a test unless there's any objections.

[mirkolenz]

I have updated/fixed the docstrings, updated the method you linked via a pytest.parametrize option, and added docs for the new feature.

[igorbrigadir]

Awesome! thanks so much! The --sort-order is fine that way, we can clean it up or refactor it later! All good to go!