Expose rkyv features as features for chrono users. #2787

Job	Run time
no_std (ubuntu-latest, thumbv6m-none-eabi)	13s
timezones (ubuntu-latest, ACST-9:30)	1m 11s
no_std (ubuntu-latest, x86_64-fortanix-unknown-sgx)	13s
timezones (ubuntu-latest, EST4)	1m 23s
timezones (ubuntu-latest, UTC0)	1m 13s
alternative_targets (ubuntu-latest, wasm32-unknown-emscripten)	21s
timezones (ubuntu-latest, Asia/Katmandu)	1m 10s
alternative_targets (ubuntu-latest, aarch64-apple-ios)	9s
alternative_targets (ubuntu-latest, aarch64-linux-android)	9s
timezones (macos-latest, ACST-9:30)	1m 9s
timezones (macos-latest, EST4)	48s
timezones (macos-latest, UTC0)	47s
check-docs	19s
timezones (macos-latest, Asia/Katmandu)	1m 16s
timezones (windows-latest, ACST-9:30)	1m 14s
cross-targets (x86_64-sun-solaris)	1m 17s
timezones (windows-latest, EST4)	1m 13s
timezones (windows-latest, UTC0)	1m 41s
cross-tests (ubuntu-latest)	1m 43s
timezones (windows-latest, Asia/Katmandu)	2m 24s
features_check (ubuntu-latest)	3m 50s
rust_versions (ubuntu-latest, stable)	53s
features_check (macos-latest)	7m 38s
rust_versions (ubuntu-latest, beta)	1m 11s
features_check (windows-latest)	7m 1s
rust_versions (ubuntu-latest, nightly)	1m 12s
test_wasi (ubuntu-latest, wasm32-wasi)	17s
test_wasm (ubuntu-latest)	15s
rust_msrv (ubuntu-latest)	10s
	42m 20s

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