Enable signing without private key #1547

Job	Run time
Format & clippy	5m 4s
Documentation (stable)	56s
Check semver compatibility	1m 3s
Documentation (nightly)	1m 1s
Validate external types appearing in public API	1m 35s
build (macOS-latest, stable)	3m 55s
Build rustls-cert-gen as a standalone package	26s
build (ubuntu-latest, stable)	5m 33s
build (ubuntu-latest, beta)	5m 39s
build (ubuntu-latest, nightly)	5m 26s
build-windows	11m 47s
build (ubuntu-latest, stable 7 months ago)	5m 48s
Measure coverage	5m 38s
	53m 51s

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