Expose rkyv features as features for chrono users. #2781

Job	Run time
cross-targets (x86_64-sun-solaris)	1m 14s
check-docs	19s
alternative_targets (ubuntu-latest, wasm32-unknown-emscripten)	27s
cross-tests (ubuntu-latest)	1m 16s
alternative_targets (ubuntu-latest, aarch64-apple-ios)	17s
no_std (ubuntu-latest, thumbv6m-none-eabi)	20s
alternative_targets (ubuntu-latest, aarch64-linux-android)	14s
features_check (ubuntu-latest)	38s
no_std (ubuntu-latest, x86_64-fortanix-unknown-sgx)	18s
features_check (macos-latest)	53s
rust_msrv (ubuntu-latest)	11s
features_check (windows-latest)	50s
rust_versions (ubuntu-latest, stable)	42s
test_wasi (ubuntu-latest, wasm32-wasi)	39s
rust_versions (ubuntu-latest, beta)	38s
test_wasm (ubuntu-latest)	33s
rust_versions (ubuntu-latest, nightly)	40s
timezones (ubuntu-latest, ACST-9:30)	23s
timezones (ubuntu-latest, EST4)	22s
timezones (ubuntu-latest, UTC0)	22s
timezones (ubuntu-latest, Asia/Katmandu)	13s
timezones (macos-latest, ACST-9:30)	44s
timezones (macos-latest, EST4)	40s
timezones (macos-latest, UTC0)	38s
timezones (macos-latest, Asia/Katmandu)	40s
timezones (windows-latest, ACST-9:30)	21s
timezones (windows-latest, EST4)	8s
timezones (windows-latest, UTC0)	1s
timezones (windows-latest, Asia/Katmandu)	2s
	14m 43s

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