Remove build RUNPATH from installed libGrid3D.so (#676)

Installs libGrid3D.so (a legacy alias for libGridConfig.so)
by copying the already installed libGridConfig.so using install(CODE ...)
instead of install(FILES ...). This ensures the build directory
RUNPATH is correctly stripped, matching other installed plugins.

Fixes #627

Signed-off-by: shashank1300 <shashankrao1307@gmail.com>
Co-authored-by: Addisu Z. Taddese <addisu@openrobotics.org>

Author: shashank1300

src/plugins/grid_config/CMakeLists.txt

@@ -7,8 +7,14 @@ gz_gui_add_plugin(GridConfig
     gz-rendering${GZ_RENDERING_VER}::gz-rendering${GZ_RENDERING_VER}
 )
 
-# Also install as Grid3D, which was a legacy plugin with a subset of features
-install (
-  FILES $<TARGET_FILE:GridConfig>
-  RENAME ${CMAKE_SHARED_LIBRARY_PREFIX}Grid3D${CMAKE_SHARED_LIBRARY_SUFFIX}
-  DESTINATION ${GZ_GUI_PLUGIN_RELATIVE_INSTALL_DIR})
+# Also install Grid3D (a legacy plugin with a subset of features) by copying the installed GridConfig library. This ensures the correct RUNPATH is used.
+
+install(CODE "
+  if(EXISTS \"\${CMAKE_INSTALL_PREFIX}/${GZ_GUI_PLUGIN_RELATIVE_INSTALL_DIR}/libGridConfig.so\")
+    execute_process(COMMAND ${CMAKE_COMMAND} -E copy_if_different
+    \"\${CMAKE_INSTALL_PREFIX}/${GZ_GUI_PLUGIN_RELATIVE_INSTALL_DIR}/libGridConfig.so\"
+    \"\${CMAKE_INSTALL_PREFIX}/${GZ_GUI_PLUGIN_RELATIVE_INSTALL_DIR}/libGrid3D.so\")
+  else()
+    message(WARNING \"Source file for Grid3D (legacy plugin) copy not found, skipping copy: \${CMAKE_INSTALL_PREFIX}/${GZ_GUI_PLUGIN_RELATIVE_INSTALL_DIR}/libGridConfig.so\")
+  endif()
+")