feat: add GracefulShutdown helper (#127) #412

Job	Run time
semver	22s
Check Style	9s
features	53s
Test with Miri	1m 5s
Check MSRV (1.63)	51s
Test stable on ubuntu-latest	48s
Test stable on windows-latest	1m 13s
Test stable on macos-latest	27s
Test beta on ubuntu-latest	40s
Test beta on windows-latest	1m 36s
Test beta on macos-latest	35s
Test nightly on ubuntu-latest	32s
Test nightly on windows-latest	1m 14s
Test nightly on macos-latest	37s
Build docs	16s
CI is green	1s
	11m 19s

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