ToolbarButton: Accepts both disabled and isDisabled props with different behavior

[mirka]

ToolbarButton is intended to be disabled with the designated isDisabled prop, judging from the code and TypeScript types.

However, it also accepts the standard disabled prop because it allows standard <button> props via restProps. To complicate things further, the disabled prop in these restProps are first passed onto Ariakit.ToolbarItem before eventually being passed down to Button, which opts out the toolbar item from the roving tabindex set regardless of whether the underlying Button allows focusable disabled.

So to allow focusable disabled, you'll need to pass a combination of either disabled & accessibleWhenDisabled (Ariakit API which is undocumented in our docs), or isDisabled & __experimentalIsFocusable.

I'm not immediately sure how we'd want to address this, but things should be less confusing. We might want to tweak the logic so that passing disabled will result in the same behavior as passing isDisabled.

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Related: #57701