[OSCBS-41] Update to Zephyr v3.2.0 (#382)

Updating to integrate with Zephyr v3.2.0 required:

- Update `west.yml` to import Zephyr v3.2.0 manifest
- Prefix include pathname of ztest.h with `zephyr/`
- Prefix every Zephyr header included pathname with `zephyr/`
- Change all Zephyr tests/samples to use `find_package`
- For unit_testing, use a distinct prj.conf which only references
  Kconfigs defined in the Zephyr repo. (Zephyr constraint.)
- Move ztest headers into a zephyr-prefixed pathname

Co-authored-by: Gregory Shue <gregory.shue@legrand.com>

test/ztest/include/zephyr/kernel.h

@@ -0,0 +1,24 @@
+/*
+ * Copyright (c) 2015 Intel Corporation
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#ifndef ZEPHYR_INCLUDE_ZEPHYR_H_
+#define ZEPHYR_INCLUDE_ZEPHYR_H_
+
+/*
+ * Applications can identify whether they are built for Zephyr by
+ * macro below. (It may be already defined by a makefile or toolchain.)
+ */
+#ifndef __ZEPHYR__
+#define __ZEPHYR__
+#endif
+
+//GAS: rm? #include <kernel.h>
+
+//GAS: add?
+#define Z_STRINGIFY(x) #x
+#define STRINGIFY(s) Z_STRINGIFY(s)
+
+#endif /* ZEPHYR_INCLUDE_ZEPHYR_H_ */