GPUI AccessKit integration
This PR is replacing #51097 , and is much more limited in scope. This PR
*ONLY* adds AccessKit support to GPUI, and doesn't touch Zed. Once this
lands, we can start adding aria attributes to Zed's components.
This PR is the first step to addressing #41138 .
Release Notes:
- N/A or Added/Fixed/Improved ...
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Co-authored-by: John Tur <john-tur@outlook.com>
Co-authored-by: Zed Zippy <234243425+zed-zippy[bot]@users.noreply.github.com>
Co-authored-by: Bennet Bo Fenner <bennetbo@gmx.de>
Co-authored-by: Agus Zubiaga <agus@zed.dev>
