Smoke

Add flattened release smoke support #44

Job	Run time
flatten / windows-latest / hardlink	34s
flatten / ubuntu-latest / hardlink	26s
ubuntu-latest / copy	26s
windows-latest / symlink	41s
windows-latest / hardlink	49s
ubuntu-latest / symlink	23s
ubuntu-latest / hardlink	29s
windows-latest / copy	1m 26s
	5m 14s

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