Add test_certs.h generate script

Signed-off-by: Jerry Yu <jerry.h.yu@arm.com>
diff --git a/tests/data_files/test_certs.h.jinja2 b/tests/data_files/test_certs.h.jinja2
new file mode 100644
index 0000000..390ea08
--- /dev/null
+++ b/tests/data_files/test_certs.h.jinja2
@@ -0,0 +1,54 @@
+/*
+ *  X.509 test certificates
+ *
+ *  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.
+ */
+
+/* THIS FILE is generated by `tests/scripts/generate_test_cert_macros.py` */
+/* *INDENT-OFF* */
+
+{% for mode, name, value in macros %}
+    {% if mode == 'string' %}
+/* This is taken from {{value}}. */
+/* BEGIN FILE string macro {{name}} {{value}} */
+#define {{name}}{{ '\\' | put_to_column(position=80-9-name|length)}}
+        {% for line in value | read_lines %}
+    "{{line}}\r\n"{% if not loop.last %}{{ '\\' | put_to_column(position=80-10-1-line|length)}}
+        {% endif %}
+        {% endfor %}
+
+/* END FILE */
+    {% endif %}
+    {% if mode == 'binary' %}
+/* This is generated from {{value}}. */
+/* BEGIN FILE binary macro {{name}} {{value}} */
+#define {{name}} {% raw -%} { {%- endraw %} {{ '\\' | put_to_column(position=80-11-name|length)}}
+    {% for line in value | read_as_c_array %}
+        {% if not loop.last %}
+        {{line}},{{ '\\' | put_to_column(position=80-9-line|length)}}
+        {% else %}
+        {{line}}{{ '\\' | put_to_column(position=80-8-line|length)}}
+        {% endif %}
+    {% endfor %}
+{% raw -%} } {%- endraw %}
+
+/* END FILE */
+    {% endif %}
+    {% if mode == 'password' %}
+#define {{name}} "{{value}}"
+    {% endif %}
+
+{% endfor %}