Add core stack headers into bacdef.h and cleanup includes. (#602)

* Added dependent BACnet stack headers into bacdef.h file.

* Changed bacdef.h and other stack includes in c/h files to have a common pattern.

* Moved bits.h, bytes.h, and bacnet_stack_exports.h under bacnet/basic/sys/ folder.

src/bacnet/basic/sys/bits.h

@@ -0,0 +1,51 @@
+/**
+ * @file
+ * @author Steve Karg
+ * @date 2022
+ * @brief Bitwise helper macros
+ * @copyright 2012 Steve Karg <skarg@users.sourceforge.net>
+ *
+ * SPDX-License-Identifier: MIT
+ */
+#ifndef BACNET_SYS_BITS_H
+#define BACNET_SYS_BITS_H
+
+/********************************************************************
+* Bit Masks
+*********************************************************************/
+#ifndef BIT
+#define BIT(x)  (1<<(x))
+#endif
+#ifndef _BV
+#define _BV(x)  (1<<(x))
+#endif
+
+/* a=register, b=bit number to act upon 0-n */
+#ifndef BIT_SET
+#define BIT_SET(a,b) ((a) |= (1<<(b)))
+#endif
+#ifndef BIT_CLEAR
+#define BIT_CLEAR(a,b) ((a) &= ~(1<<(b)))
+#endif
+#ifndef BIT_FLIP
+#define BIT_FLIP(a,b) ((a) ^= (1<<(b)))
+#endif
+#ifndef BIT_CHECK
+#define BIT_CHECK(a,b) ((a) & (1<<(b)))
+#endif
+
+/* x=target variable, y=mask */
+#ifndef BITMASK_SET
+#define BITMASK_SET(x,y) ((x) |= (y))
+#endif
+#ifndef BITMASK_CLEAR
+#define BITMASK_CLEAR(x,y) ((x) &= (~(y)))
+#endif
+#ifndef BITMASK_FLIP
+#define BITMASK_FLIP(x,y) ((x) ^= (y))
+#endif
+#ifndef BITMASK_CHECK
+#define BITMASK_CHECK(x,y) (((x) & (y)) == (y))
+#endif
+
+#endif