Add extensions on `DateTime` and `List` #485

Job	Run time
build_fetch (ubuntu-latest)	49s
build_checkout (dev, ubuntu-latest)	2m 31s
build_fetch (windows-latest)	1m 8s
build_checkout (dev, windows-latest)	5m 12s
build_fetch (macos-latest)	55s
build_local (ubuntu-latest)	1m 52s
build_checkout (dev, macos-latest)	2m 27s
build_local (macos-latest)	1m 54s
build_local (windows-latest)	3m 22s
	20m 10s

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