Support requesting latest nightly with `tools: nightly` #4670

Job	Run time
Resolve environment (ubuntu-latest, default)	39s
Resolve environment (macos-latest, linked)	1m 53s
Resolve environment (ubuntu-latest, linked)	35s
Resolve environment (macos-latest, default)	1m 46s
Resolve environment (windows-latest, default)	1m 12s
Resolve environment (ubuntu-latest, nightly-latest)	35s
Resolve environment (windows-latest, nightly-latest)	5m 0s
Resolve environment (macos-latest, nightly-latest)	2m 22s
Resolve environment (windows-latest, linked)	1m 24s
	15m 26s

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