[x509] Encode EC_KEY as SubjectPublicKeyInfo

This cl adds bssl wrappers that enable the encoding of bssl::EC_KEY
objects as SubjectPublicKeyInfo. This will facilitate the econding
of the public key in the client VM's CSR in the x509 certificate
later.

Test: atest libbssl_avf_nostd.test
Bug: 309441500
Change-Id: I374a4a9d7e9ff5408cd176dfca09b670da507e11
diff --git a/libs/bssl/src/lib.rs b/libs/bssl/src/lib.rs
index 8e3abcf..e378386 100644
--- a/libs/bssl/src/lib.rs
+++ b/libs/bssl/src/lib.rs
@@ -24,6 +24,7 @@
 mod digest;
 mod ec_key;
 mod err;
+mod evp;
 mod hkdf;
 mod hmac;
 mod rand;
@@ -37,6 +38,7 @@
 pub use cbs::Cbs;
 pub use digest::Digester;
 pub use ec_key::{EcKey, ZVec};
+pub use evp::EvpPKey;
 pub use hkdf::hkdf;
 pub use hmac::hmac_sha256;
 pub use rand::rand_bytes;