Added Zephyr settings and basic device in subsys. (#697)

* Added Zephyr settings subsys to enable storing of BACnet values according to BACnet object property value path.

* Added BACnet Basic features to enable basic samples. Refactored the zephyr BACnet profile B-SS sample to use BACnet basic subsys.

zephyr/subsys/bacnet_shell.c

@@ -0,0 +1,12 @@
+/**
+ * @file
+ * @brief The BACnet shell commands for debugging and testing
+ * @author Greg Shue <greg.shue@outlook.com>
+ * @date May 2024
+ * @copyright SPDX-License-Identifier: MIT
+ */
+#include <zephyr/shell/shell.h>
+
+SHELL_SUBCMD_SET_CREATE(sub_bacnet_cmds, (bacnet));
+
+SHELL_CMD_REGISTER(bacnet, &sub_bacnet_cmds, "BACnet module", NULL);