Remove EVP_PKEY_ASN1_METHOD and EVP_PKEY_METHOD from public headers

With EVP_PKEY and EVP_PKEY_CTX opaque, these symbols don't appear in any
public APIs anymore. Make them internal, which also opens the door to
renaming them:

- EVP_PKEY_METHOD is more accurately EVP_PKEY_CTX_METHOD
- EVP_PKEY_ASN1_METHOD is more accurately EVP_PKEY_METHOD

Or perhaps the split doesn't mean much and we should fold them together.

Change-Id: I8a0f7c2e07445dc981c7cef697263e59dba7784e
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/57885
Commit-Queue: David Benjamin <[email protected]>
Auto-Submit: David Benjamin <[email protected]>
Reviewed-by: Bob Beck <[email protected]>
Commit-Queue: Bob Beck <[email protected]>
(cherry picked from commit a925c220c123af0bdd49be3a8a84a506584c1fb2)

crypto/evp_extra/internal.h

@@ -2,6 +2,7 @@
 // SPDX-License-Identifier: Apache-2.0 OR ISC
 
 #include <openssl/base.h>
+#include "../fipsmodule/evp/internal.h"
 
 typedef struct {
   // key is the concatenation of the private seed and public key. It is stored

crypto/fipsmodule/evp/internal.h

@@ -70,6 +70,9 @@ extern "C" {
 // |EVP_MD_CTX_set_pkey_ctx|.
 #define EVP_MD_CTX_FLAG_KEEP_PKEY_CTX   0x0400
 
+typedef struct evp_pkey_asn1_method_st EVP_PKEY_ASN1_METHOD;
+typedef struct evp_pkey_method_st EVP_PKEY_METHOD;
+
 struct evp_pkey_asn1_method_st {
   int pkey_id;
   uint8_t oid[11];

include/openssl/base.h

@@ -431,9 +431,7 @@ typedef struct evp_hpke_kem_st EVP_HPKE_KEM;
 typedef struct evp_hpke_key_st EVP_HPKE_KEY;
 typedef struct evp_kem_st EVP_KEM;
 typedef struct kem_key_st KEM_KEY;
-typedef struct evp_pkey_asn1_method_st EVP_PKEY_ASN1_METHOD;
 typedef struct evp_pkey_ctx_st EVP_PKEY_CTX;
-typedef struct evp_pkey_method_st EVP_PKEY_METHOD;
 typedef struct evp_pkey_st EVP_PKEY;
 typedef struct hmac_ctx_st HMAC_CTX;
 typedef struct md4_state_st MD4_CTX;