Support more private key formats when using aws_lc_rs feature #1223

Job	Run time
Validate external types appearing in public API	1m 35s
build-windows	9m 31s
build (macOS-latest, stable)	27s
Build rustls-cert-gen as a standalone package	21s
build (ubuntu-latest, stable)	21s
Measure coverage	5m 44s
Format & clippy	5m 24s
build (ubuntu-latest, beta)	23s
Documentation (stable)	51s
build (ubuntu-latest, nightly)	27s
Check semver compatibility	57s
build (ubuntu-latest, stable 7 months ago)	26s
Documentation (nightly)	1m 1s
	27m 28s

Provide feedback