Support compiling without cryptography primitives (#208) #900

Job	Run time
Validate external types appearing in public API	1m 17s
Clippy (--all-features)	4m 53s
Clippy (--no-default-features)	4m 40s
Format	7s
Clippy (--no-default-features --features ring)	4m 36s
Documentation (stable)	39s
Clippy (--no-default-features --features aws_lc_rs)	4m 43s
Documentation (beta)	41s
build-windows	12m 4s
Clippy (--no-default-features --features aws_lc_rs,pem)	4m 40s
Documentation (nightly)	43s
Check semver compatibility	32s
Documentation (stable 7 months ago)	49s
build (macOS-latest, stable)	1m 2s
Build rustls-cert-gen as a standalone package	28s
build (ubuntu-latest, stable)	5m 27s
build (ubuntu-latest, beta)	5m 56s
Measure coverage	32s
build (ubuntu-latest, nightly)	5m 54s
build (ubuntu-latest, stable 7 months ago)	44s
	1h 0m 27s

Provide feedback