Support requesting latest nightly with `tools: nightly` #4665

Job	Run time
Resolve environment (windows-latest, nightly-latest)	1m 28s
Resolve environment (macos-latest, default)	1m 49s
Resolve environment (ubuntu-latest, default)	38s
Resolve environment (windows-latest, linked)	1m 33s
Resolve environment (macos-latest, nightly-latest)	1m 47s
Resolve environment (ubuntu-latest, nightly-latest)	37s
Resolve environment (macos-latest, linked)	2m 7s
Resolve environment (ubuntu-latest, linked)	41s
Resolve environment (windows-latest, default)	1m 34s
	12m 14s

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