django-selectable -> django-autocomplete-light

[rabstejnek]

Replace django-selectable (no longer supported) with django-autocomplete-light.

In addition:

• remove jquery UI
• update [htmx] (https://github.com/bigskysoftware/htmx/blob/master/CHANGELOG.md) 1.6.1 -> 1.8.0
• write a new client-side autocomplete method now that jquery UI is removed

[shapiromatron]

This is great work. After we complete laying the framework here, we'll probably progressively work through the app, replacing one lookups.py file at at a time...

[rabstejnek]

@shapiromatron ready for review!

[shapiromatron]

Excited to merge this in! Really big and complicated PR, the autocomplete abstractions look very convenient and easy to use. I changed the single file into a package to give it some room to grow, and made a few other minor changes, but the bones of this PR were solid and clearly very well tested and designed.

Excellent job! Goodbye django-selectable, you've served us well (and also jquery UI).

We will have to figure out how to deal with this flaky epiv2 integration test a little further down the road...