Sliders aria-valuetext should match output element

^{Originally posted by **robin-kestrel** May 17, 2024}
The `Slider` component currently accepts a `formatOptions` prop; if specified, it is used in conjunction with `Intl.NumberFormat` to (a) set the content of the `SliderOutput` component and (b) set the `aria-valuetext` property on the `input` hidden inside each `Thumb` component.

This API is perfectly fine for simple cases, but seems limiting for more complex ones. [Here's a sandbox with some motivating examples.](https://codesandbox.io/p/devbox/recursing-dubinsky-77kpw7?file=%2Fsrc%2FApp.tsx%3A4%2C10) The first group of sliders shows what is currently possible; the second group of sliders shows what I think is _almost_ currently possible. Replacing the `SliderOutput` component with a custom label is trivial, but propagating that label to the `aria-valuetext` property of the corresponding input doesn't seem like it's currently doable — at least, not without a lot of messing around with hooks.

Is there an option I'm missing that would allow custom labels to be propagated to `aria-valuetext`, for screen readers to pick up? If not, could such an option be added? The simplest thing that comes to mind is a `format` prop for the `Slider` component that would accept a `(value: number) => string`, and would otherwise function basically the same way as `formatOptions` does now.