tests: Add tests for HDR Static Metadata encoding/decoding and equality

We have the drm/InfoFrame encoding and our MetaOutputHdrMetadata
encoding. Check that we can correctly convert between each other by
doing a encode/decode and decode/encode roundtrip and then checking for
equality.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2879>

src/tests/hdr-metadata-unit-tests.h

@@ -0,0 +1,26 @@
+/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*- */
+/*
+ * Copyright (C) 2023 Red Hat Inc.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <http://www.gnu.org/licenses/>.
+ *
+ * Author: Sebastian Wick <sebastian.wick@redhat.com>
+ */
+
+#ifndef HDR_METADATA_UNIT_TESTS_H
+#define HDR_METADATA_UNIT_TESTS_H
+
+void init_hdr_metadata_tests (void);
+
+#endif /* HDR_METADATA_UNIT_TESTS_H */