Add from_timestamp_nanos #2758

Job	Run time
check-docs	23s
alternative_targets (ubuntu-latest, wasm32-unknown-emscripten)	17s
alternative_targets (ubuntu-latest, aarch64-apple-ios)	13s
cross-targets (x86_64-sun-solaris)	1m 45s
alternative_targets (ubuntu-latest, aarch64-linux-android)	14s
cross-tests (ubuntu-latest)	2m 28s
features_check (ubuntu-latest)	5m 55s
features_check (macos-latest)	14m 29s
features_check (windows-latest)	9m 22s
no_std (ubuntu-latest, thumbv6m-none-eabi)	14s
no_std (ubuntu-latest, x86_64-fortanix-unknown-sgx)	17s
rust_msrv (ubuntu-latest)	1m 22s
rust_versions (ubuntu-latest, stable)	1m 1s
test_wasi (ubuntu-latest, wasm32-wasi)	21s
rust_versions (ubuntu-latest, beta)	1m 17s
rust_versions (ubuntu-latest, nightly)	2m 38s
test_wasm (ubuntu-latest)	15s
timezones (ubuntu-latest, ACST-9:30)	1m 16s
timezones (ubuntu-latest, EST4)	1m 34s
timezones (ubuntu-latest, UTC0)	1m 18s
timezones (ubuntu-latest, Asia/Katmandu)	1m 17s
timezones (macos-latest, ACST-9:30)	43s
timezones (macos-latest, EST4)	1m 40s
timezones (macos-latest, UTC0)	55s
timezones (macos-latest, Asia/Katmandu)	54s
timezones (windows-latest, ACST-9:30)	2m 39s
timezones (windows-latest, EST4)	2m 41s
timezones (windows-latest, UTC0)	2m 35s
timezones (windows-latest, Asia/Katmandu)	1m 48s
	1h 1m 51s

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