Refactor nested dropdown to have the same keyboard shortcut of the main list
Allow the opening of the nested dropdown with ArrowRight
Allow the closing of the nested dropdown with ArrowLeft and Escape
Set focus on nested dropdown trigger when closing the nested dropdown
Manage the opening and closing of the nested dropdown with an internal listener
instead of an external state
Remove timeouts where possible

refs: CDS-182 CDS-138 CDS-70

Set tabindex to -1 to allow to external container to get focus
programmatically only. When grid get focused, set the focus to the primary
button.

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…entinel-elements-white-items-at-the-top-and-end-of-the-list-and-update-the-logic-of-the-keyboard-navigation-to-consider-the-first-and-last-elements-as-start-and-end-sentinels-for-the-keyboard-navigation