chore(cmake): make RTI codegen macro tolerant when RTI is not installed (skip RTIDDSGEN)

cmake/MacroRTIDDSGen.cmake

@@ -13,13 +13,18 @@
 
 
 
-MACRO(RTIDDSGEN srcList infile)
-  FIND_PACKAGE(RTI REQUIRED)
-
-  SET(input ${infile})
-  IF(NOT IS_ABSOLUTE ${input})
-    SET(input "${CMAKE_CURRENT_BINARY_DIR}/${input}")
-  ENDIF()
+MACRO(RTIDDSGEN srcList infile)
+  # RTI (DDS) code generation is optional during migration; if RTI is not found, skip code generation.
+  FIND_PACKAGE(RTI)
+  if (NOT RTI_FOUND)
+    message(STATUS "RTI not found; skipping RTI IDL code generation for ${infile}")
+    return()
+  endif()
+
+  SET(input ${infile})
+  IF(NOT IS_ABSOLUTE ${input})
+    SET(input "${CMAKE_CURRENT_BINARY_DIR}/${input}")
+  ENDIF()
   GET_FILENAME_COMPONENT(output  ${infile} NAME_WE)
   GET_FILENAME_COMPONENT(input   ${input} ABSOLUTE)