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/include/bacnet_basic/bacnet_basic.h

@@ -0,0 +1,25 @@
+/**
+ * @file
+ * @brief BACnet Basic Stack initialization and basic task handler
+ * @author Steve Karg <skarg@users.sourceforge.net>
+ * @date April 2024
+ * @copyright SPDX-License-Identifier: MIT
+ */
+#ifndef BACNET_BASIC_H
+#define BACNET_BASIC_H
+
+#include <stdint.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif /* __cplusplus */
+
+void bacnet_basic_init(void);
+void bacnet_basic_task(void);
+unsigned long bacnet_basic_uptime_seconds(void);
+unsigned long bacnet_basic_packet_count(void);
+
+#ifdef __cplusplus
+}
+#endif /* __cplusplus */
+#endif