Create a directory for maintainer-only Python scripts

This directory is currently excluded from `check-python-files.sh`, because
we run it on the CI in an old Python version that doesn't support some of
our new maintainer scripts.

There are no such scripts in mbedtls for now (only in TF-PSA-Crypto), but be
ready if we want to add some.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>

scripts/maintainer/maintainer_scripts_path.py

@@ -0,0 +1,20 @@
+"""Add our Python library directories for maintainer scripts to the module search path.
+
+Usage:
+
+    import maintainer_scripts_path # pylint: disable=unused-import
+"""
+
+# Copyright The Mbed TLS Contributors
+# SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
+#
+
+import os
+import sys
+
+sys.path.append(os.path.join(os.path.dirname(__file__),
+                             os.path.pardir, os.path.pardir,
+                             'framework', 'scripts'))
+sys.path.append(os.path.join(os.path.dirname(__file__),
+                             os.path.pardir, os.path.pardir,
+                             'framework', 'util'))