Add OS specific settings (#35756)

Release Notes:

- Settings can now be configured per operating system with the new
top-level fields: `"macos"`/`"windows"`/`"linux"`. These will override
user level settings, but are lower precedence than _release channel_
settings.
e2e147ab0eJulia Ryan committed on 8/7/2025, 5:52:54 PM· committed by GitHubparentfa2ff3c
4 files changedLine totals unavailable