CustomSelect: disable virtualFocus to fix issue for screenreaders

[brookewp]

What?

@afercia pointed out an issue in Safari for screenreaders, where multi-selection has incorrect announcements:

#55023 (comment)

Why?

Unfortunately, it appears it still hasn't been resolved in Safari, so in preparation for the component to be utilized (#57902), we should have a working solution.

How?

@diegohaz shared this is a bug in Safari and a solution to use in the meantime: #55023 (comment)

Safari has known issues with aria-activedescendant. It appears the issue is being addressed for combobox widgets in the upcoming version. So, we can expect improvements in the near future.

For now, the aria-activedescendant can be disabled for the Ariakit Select component by setting the virtualFocus prop to false. This will enable the use of the roving tabindex approach, which seems to function well on Safari.

Testing Instructions

1. npm run:storybook dev
2. While using a screen reader, open the select for the 'Multiselect' story.
3. Ensure it announces the names of unselected items, rather than saying they are selected

Before	After

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Props: brookemk, 0mirka00, hazdiego.

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Co-authored-by: brookewp <brookemk@git.wordpress.org>
Co-authored-by: mirka <0mirka00@git.wordpress.org>
Co-authored-by: diegohaz <hazdiego@git.wordpress.org>

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[mirka]

Confirmed working in Safari 👍

Unfortunately I'm still seeing unreliable announcements with VoiceOver on Firefox. It happens regardless of the changes in this PR, so I think we can still land it as an incremental improvement.

[diegohaz]

Unfortunately I'm still seeing unreliable announcements with VoiceOver on Firefox. It happens regardless of the changes in this PR, so I think we can still land it as an incremental improvement.

Just to pile on a bit more info, according to the latest WebAIM survey, the VoiceOver/Firefox combo is quite uncommon. It doesn't even make the list.