Compute syntax smart tags for utterances with multiple sentences.

[gabegma]

Resolve #434

Description:

• This will make it easier for datasets with long utterances (with multiple sentences) to have meaningful syntax smart tags.
• This will enable us to display the long/short utterances on the token count plot.
• I took this opportunity to refactor the syntax tagging tests, so they test all results (they also weren't working because of using all instead of any.)

Checklist:

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  our users.
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  • Update the documentation if this PR changes how to develop/launch on the app.
  • Update the README files and our wiki for any big design decisions, if relevant.
  • Add unit tests, docstrings, typing and comments for complex sections.

[JosephMarinier]

Cool! And good catch! 👍 I just have small ideas to improve the tests.