Reland "CloseAll: Hide combine desks when no app windows"

This is a reland of commit 9b625831d3afa539d167410f08056f8e02f1efbd
It fixes the HideCombineDesksOptionsWhenNoWindowsOnDesk test by having
the mouse hover over the desk preview (making the DeskActionView
visible) before checking the combine desks button's visibility.

Original change's description:
> CloseAll: Hide combine desks when no app windows
>
> This CL updates the DeskActionView and the DeskActionContextMenu to hide
> the combine desks option in both components when there are no app
> windows open on the respective desk.
>
> Bug: 1319613
> Change-Id: I5db777b565f4454945067f9282d22e93557795f9
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3611029
> Reviewed-by: Sammie Quon <sammiequon@chromium.org>
> Commit-Queue: Ben Becker <benbecker@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#998690}

Bug: 1319613
Change-Id: Ic6f143114fce9dc15113b2403b5867ccdd0ddee3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3624779
Reviewed-by: Sammie Quon <sammiequon@chromium.org>
Commit-Queue: Ben Becker <benbecker@chromium.org>
Cr-Commit-Position: refs/heads/main@{#998979}