Support requesting latest nightly with `tools: nightly` #5089

Job	Run time
Diagnostic export (windows-latest, nightly-latest)	2m 10s
Diagnostic export (macos-latest, nightly-latest)	1m 6s
Diagnostic export (windows-latest, linked)	1m 35s
Diagnostic export (ubuntu-latest, nightly-latest)	59s
Diagnostic export (ubuntu-latest, linked)	1m 0s
Diagnostic export (macos-latest, linked)	1m 37s
	8m 27s

Provide feedback