Move TLS 1.3 client hello writing to new TLS 1.2 and 1.3 client file

Signed-off-by: Ronald Cron <ronald.cron@arm.com>

library/ssl_client.h

@@ -0,0 +1,33 @@
+/**
+ *  TLS 1.2 and 1.3 client-side functions
+ *
+ *  Copyright The Mbed TLS Contributors
+ *  SPDX-License-Identifier: Apache-2.0
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License"); you may
+ *  not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *  http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+
+#ifndef MBEDTLS_SSL_CLIENT_H
+#define MBEDTLS_SSL_CLIENT_H
+
+#include "common.h"
+
+#if defined(MBEDTLS_SSL_TLS_C)
+#include "ssl_misc.h"
+#endif
+
+#include <stddef.h>
+
+int mbedtls_ssl_write_client_hello( mbedtls_ssl_context *ssl );
+
+#endif /* MBEDTLS_SSL_CLIENT_H */