WT-851 Update navigation state correctly on click

[bluewave41]

One-line summary

The navigation bar closes and opens the panel when clicked instead of just closing. This is because is contains a focus handler as well as a click handler which both run when clicked.

Issue / Bugzilla link

https://mozilla-hub.atlassian.net/browse/WT-851

Testing

• Checkout this PR
• Hover over an item in the navigation (Browser) ensuring the drop down appears
• Move around each title ensuring the menus appear and disappear correctly
• Tab into a menu and hit enter. The panel should appear.
• Tab into the next panel. The previous panel should disappear
• Tab out of the final panel (Resources). The menu should disappear
• Shift+Tab out out of the first panel (Browser). The menu should disappear

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 79.54%. Comparing base (f605e65) to head (88ba464).
⚠️ Report is 16 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1242      +/-   ##
==========================================
+ Coverage   79.25%   79.54%   +0.28%     
==========================================
  Files         135      138       +3     
  Lines        8375     8574     +199     
==========================================
+ Hits         6638     6820     +182     
- Misses       1737     1754      +17     

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[bluewave41]

I'll keep the labels in mind from now on :)

[maureenlholland]

it's not required, I do it for myself because I find the labels easier to see at a glance than whether or not the PR's in draft

[janriokrause]

Tested and works for me, but leaving the approval to the front-end team.

💡 Idea: We could drop focusedMenu if we switch the mouse handler from click to pointerdown and add a keyboard keydown handler (Enter/Space). pointerdown fires before focus/click, so it avoids the focus -> click double‑toggle that caused the re‑open. Hover behavior stays the same.