Add multi-device support for BACnet gateway routing (#1279)

* Expanded Object_List to Object_List[MAX_NUM_DEVICES] array to support per-device objects for virtual remote devices
* Added multi-device iteration for COV handler, device timer, and intrinsic reporting
* Added apps/gateway2 demo application
* When MAX_NUM_DEVICES == 1, behavior is identical to the original implementation
* Conditional compilation with macros ensures no impact on non-gateway applications

---------

Signed-off-by: Hyeongjun Kim <hjun1.kim@samsung.com>
Co-authored-by: haemeok-kang <haemeok.kang@samsung.com>

CMakeLists.txt

@@ -1022,6 +1022,15 @@ if(BACNET_STACK_BUILD_APPS)
     )
   endif()
 
+  if(BAC_ROUTING)
+    add_executable(gateway2 apps/gateway2/main.c apps/gateway2/gateway.h)
+    target_link_libraries(gateway2 PRIVATE ${PROJECT_NAME})
+    target_compile_options(gateway2 PRIVATE
+      # Unreachable code because we have endless loop.
+      $<$<C_COMPILER_ID:MSVC>:/wd4702>
+    )
+  endif()
+
   add_executable(getevent apps/getevent/main.c)
   target_link_libraries(getevent PRIVATE ${PROJECT_NAME})