[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/bacnet/datetime/src/main.c

@@ -42,7 +42,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <ctype.h>
-#include <ztest.h>
+#include <zephyr/ztest.h>
 #include "bacnet/datetime.h"
 #include "bacnet/bacdcode.h"