[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>

zephyr/subsys/object/device.c

@@ -7,7 +7,7 @@
 /** @file device.c Zephyr specific part of the Base "class". */
 
 #ifdef CONFIG_BACNET_USE_SECTION_ITERABLE_OBJECT_TABLE
-#include <zephyr.h>
+#include <zephyr/kernel.h>
 #endif
 #include "bacnet/basic/object/device.h"
 #include "object.h"

zephyr/subsys/object/object.h

@@ -5,7 +5,7 @@
  */
 
 #ifndef ZTEST_UNITTEST
-  #include <zephyr.h>
+  #include <zephyr/kernel.h>
 #else
   #include "stdlib.h"
   #define k_malloc(a) malloc(a)