Our Asana integration was broken because they completely rewrote their

Python API. This change fixes that up, and modernizes things a bit.

Here's the full scope of changes:

Pin the asana dependency version so this doesn't happen again.
Update our API calls for the new version.
Updated Python and JS code to add type hints and use spina where

  appropriate.
Updated the CSS to support dark mode for the field contents (when not

  in edit mode).
Overrode some CSS for the selectize field while editing to allow the

  contents to fill the available space, and wrap items within the field

  rather than showing everything in a single line.
Tweaked some of the sizes and spacing for task items to look nicer.

Once we end up creating our own autocomplete controls, I'd really like

to ditch selectize. For now, this is a big improvement on what we had.

Ran setup.py develop
Added an Asana integration. Verified that putting in a correct

  personal access token loaded the workspaces, and that an incorrect one

  showed an error.
Tested searching for and adding tasks.
Tested removing tasks.
Tested that wrapping worked correctly within the selectize field, and

  that moving the cursor and editing within the wrapped field worked

  correctly.
Verified the appearance in both light and dark modes.