EVP: Add evp_keymgmt_fetch_from_prov()

This is an internal function to fetch a keymgmt method from a specific
provider.
Reviewed-by: NTomas Mraz <tomas@openssl.org>
Reviewed-by: NMatt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/16725)

crypto/evp/evp_local.h

@@ -298,6 +298,9 @@ void evp_generic_do_all(OSSL_LIB_CTX *libctx, int operation_id,
 /* Internal fetchers for method types that are to be combined with others */
 EVP_KEYMGMT *evp_keymgmt_fetch_by_number(OSSL_LIB_CTX *ctx, int name_id,
                                          const char *properties);
+EVP_KEYMGMT *evp_keymgmt_fetch_from_prov(OSSL_PROVIDER *prov,
+                                         const char *name,
+                                         const char *properties);
 
 /* Internal structure constructors for fetched methods */
 EVP_MD *evp_md_new(void);

crypto/evp/keymgmt_meth.c

@@ -213,6 +213,17 @@ EVP_KEYMGMT *evp_keymgmt_fetch_by_number(OSSL_LIB_CTX *ctx, int name_id,
                                        (void (*)(void *))EVP_KEYMGMT_free);
 }
 
+EVP_KEYMGMT *evp_keymgmt_fetch_from_prov(OSSL_PROVIDER *prov,
+                                         const char *name,
+                                         const char *properties)
+{
+    return evp_generic_fetch_from_prov(prov, OSSL_OP_KEYMGMT,
+                                       name, properties,
+                                       keymgmt_from_algorithm,
+                                       (int (*)(void *))EVP_KEYMGMT_up_ref,
+                                       (void (*)(void *))EVP_KEYMGMT_free);
+}
+
 EVP_KEYMGMT *EVP_KEYMGMT_fetch(OSSL_LIB_CTX *ctx, const char *algorithm,
                                const char *properties)
 {