Refactor stimulus nav controllers to follow stimulus best practices

[martinemde]

Change nav stimulus controllers to be more true to stimulus best practices (and be much simpler).

Also fixes the original error that triggered this PR.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (89b2171) 97.13% compared to head (16ea06d) 97.13%.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #4422   +/-   ##
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  Coverage   97.13%   97.13%           
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  Files         385      385           
  Lines        8200     8200           
=======================================
  Hits         7965     7965           
  Misses        235      235           

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[martinemde]

I made a major refactor of these now that @colby-swandale got me started on learning more about stimulus.

The header search box has some very weird behavior. I hid it on the home page, but it doesn't always solve the problem. Sometimes you can tab to it and then it stays visible, so I started hiding it purposely when the sandwich is clicked to close. It's better than it was, but you can still get in a weird state depending on the browser behavior for tabbing.

[martinemde]

The CSS changes are flipping the logic from is-expanded to hidden to be in line with the stimulus-dropdown component (which I'm not using, but still conformed to for simplicity).

[simi]

Looks good to me, but I'm total stimulus noob. Better to wait for @colby-swandale review. 🙏

[martinemde]

Hey, I'm going to merge this so I can use it as a base for autocomplete and fix the console errors. If there's any feedback, please let me know and I'll update.