x509-cert: make `RelativeDistinguishedName` field private (#1510) #1364

Job	Run time
build (1.65.0, thumbv7em-none-eabi)	1m 51s
test (1.65.0)	2m 3s
build (1.65.0, wasm32-unknown-unknown)	1m 45s
test (stable)	30s
build (stable, thumbv7em-none-eabi)	22s
build (stable, wasm32-unknown-unknown)	17s
minimal-versions / minimal-versions	36s
	7m 24s

Provide feedback