This exposes the features needed to mimic Chrome's ClientHello, which is useful
in testing. Also use bssl_shim's scopers for SSL objects.
Change-Id: Icb88bb00c0a05c27610134d618f466a24f7f757a
Reviewed-on: https://boringssl-review.googlesource.com/4113
Reviewed-by: Adam Langley <agl@google.com>