Extract shared Apple renderer from gpui_macos (#62649)

Extract parts of `platform_macos` to `gpui_apple` to be used as a shared
crate between `gpui_macos` and a future `gpui_ios` for iOS/iPadOS apps.

Release Notes:

- N/A
52b2418110Anthony Eid committed on 8/14/2026, 7:53:25 PM· committed by GitHubparenta21007b
15 files changedLine totals unavailable