feat: keyboard support for Dropdown ComboBox

[wflore19]

Description ✏️

Closes #271
related to PR #329

• Adds keyboard support for Dropdown combobox

(The background color on hover does not appear in my recording software but here's what it looks like)

• Changes functionality of <MultiComboBox />
• Updates all <MultiComboBox /> implementations

Type of Change 🐞

• Feature - A non-breaking change which adds functionality.
• Fix - A non-breaking change which fixes an issue.
• Refactor - A change that neither fixes a bug nor adds a feature.
• Documentation - A change only to in-code or markdown documentation.
• Tests - A change that adds missing unit/integration tests.
• Chore - A change that is likely none of the above.

Checklist ✅

• I have done a self-review of my code.
• I have manually tested my code (if applicable).
• I have added/updated any relevant documentation (if applicable).

[wflore19]

I'm going to double check and work on this with my Bloomberg mentor 📝

[wflore19]

Someone from Supabase implemented a better MultiCombobox w/ keyboard support.

demo: https://supabase-design-system.vercel.app/design-system/docs/fragments/multi-select#badge-combo-box
source code: https://github.com/supabase/supabase/blob/master/packages/ui-patterns/multi-select/multi-select.tsx