[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>

ports/zephyr/main.c

@@ -8,14 +8,14 @@
 #include <stdint.h>
 
 /* Zephyr includes */
-#include <init.h>
-#include <kernel.h>
-#include <sys/printk.h>
-#include <sys/util.h>
-#include <zephyr.h>
+#include <zephyr/init.h>
+#include <zephyr/kernel.h>
+#include <zephyr/sys/printk.h>
+#include <zephyr/sys/util.h>
+#include <zephyr/kernel.h>
 
 #define LOG_LEVEL CONFIG_BACNETSTACK_LOG_LEVEL
-#include <logging/log.h>
+#include <zephyr/logging/log.h>
 LOG_MODULE_REGISTER(bacnet);
 
 /* To do:  init()