tls: support "BEGIN TRUSTED CERTIFICATE" for ca:

Support the same PEM certificate formats for the ca: option to
tls.createSecureContext() that are supported by openssl when loading a
CAfile.

Fixes: https://github.com/nodejs/node/issues/24761

PR-URL: https://github.com/nodejs/node/pull/24733


Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>