Support visionOS, watchOS, and tvOS #187

Job	Run time
macos-docs	3m 1s
ios-check (stable, aarch64-apple-ios)	1m 28s
cargo-publish	0s
apple-tier-3-check (aarch64-apple-visionos)	39s
ios-check (stable, x86_64-apple-ios)	1m 30s
apple-tier-3-check (aarch64-apple-visionos-sim)	47s
ios-check (stable, aarch64-apple-ios-sim)	1m 29s
macos-test (stable)	1m 20s
apple-tier-3-check (aarch64-apple-watchos)	43s
ios-check (nightly, aarch64-apple-ios)	1m 24s
macos-test (nightly)	2m 23s
apple-tier-3-check (aarch64-apple-watchos-sim)	45s
ios-check (nightly, x86_64-apple-ios)	1m 34s
apple-tier-3-check (aarch64-apple-tvos)	37s
ios-check (nightly, aarch64-apple-ios-sim)	1m 22s
apple-tier-3-check (aarch64-apple-tvos-sim)	42s
	19m 44s

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