dropdown: the `arrow-down`/`arrow-up` keys should open a dropdown

[driskull]

Check existing issues

• [x] I have checked for existing issues to avoid duplicates

Summary

dropdown: the arrow-down/arrow-up keys should open a dropdown

Actual Behavior

Arrow keys have no effect.

Expected Behavior

Using the arrow keys on a trigger should open the dropdown component.

Reproduction Sample

https://codepen.io/driskull/pen/RwvxBZG?editors=1000

Reproduction Steps

1. focus on the "plus" action
2. Use arrow down or arrow up key
3. Nothing happens

Reproduction Version

1.10

Working W3C Example/Tutorial

https://developer.mozilla.org/en-US/docs/Web/Accessibility/ARIA/Roles/menu_role#keyboard_interactions

Relevant Info

Regression?

No response

Priority impact

p2 - want for current milestone

Calcite package

• [X] @esri/calcite-components
• [ ] @esri/calcite-components-react
• [ ] @esri/calcite-design-tokens
• [ ] @esri/eslint-plugin-calcite-components

Esri team

ArcGIS Maps SDK for JavaScript