Implement lossless From methods for Duration conversions #611

Job	Run time
Check	13s
Coverage	43s
Lints	21s
no-std build (aarch64-unknown-none)	23s
Test Suite (ubuntu-latest, MSRV)	3m 2s
no-std build (thumbv6m-none-eabi)	23s
Test Suite (ubuntu-latest, stable)	3m 7s
Test Suite (macos-latest, MSRV)	1m 50s
Test Suite (macos-latest, stable)	2m 9s
Test Suite (windows-latest, MSRV)	9m 7s
Test Suite (windows-latest, stable)	10m 8s
Release	0s
	31m 26s

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