test: add utility function to set the fake random callback on both the public and private instances

Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Shane Lontis <shane.lontis@oracle.com>
(Merged from https://github.com/openssl/openssl/pull/14341)
diff --git a/test/testutil.h b/test/testutil.h
index 8989b1f..8457a2a 100644
--- a/test/testutil.h
+++ b/test/testutil.h
@@ -567,11 +567,16 @@
 void test_random_seed(uint32_t sd);
 
 /* Fake non-secure random number generator */
+typedef int fake_random_generate_cb(unsigned char *out, size_t outlen,
+                                    const char *name, EVP_RAND_CTX *ctx);
+
 OSSL_PROVIDER *fake_rand_start(OSSL_LIB_CTX *libctx);
 void fake_rand_finish(OSSL_PROVIDER *p);
 void fake_rand_set_callback(EVP_RAND_CTX *ctx,
                             int (*cb)(unsigned char *out, size_t outlen,
                                       const char *name, EVP_RAND_CTX *ctx));
+void fake_rand_set_public_private_callbacks(OSSL_LIB_CTX *libctx,
+                                            fake_random_generate_cb *cb);
 
 /* Create a file path from a directory and a filename */
 char *test_mk_file_path(const char *dir, const char *file);