CMake: Remove LINUX_LOCAL_DEV and symlink required files

CMake/DolphinSymlinkOrCopy.cmake

@@ -0,0 +1,20 @@
+if(NOT DEFINED target OR NOT DEFINED link)
+    message(FATAL_ERROR "`target` and `link` must be defined")
+endif()
+
+file(CREATE_LINK "${target}" "${link}" RESULT result SYMBOLIC)
+if(result EQUAL 0)
+  return()
+endif()
+
+if(WIN32)
+  set(hint "On Windows, enable Developer Mode to allow symlinks (https://learn.microsoft.com/windows/advanced-settings/developer-mode).")
+endif()
+message(WARNING "Symlink failed (${result}). Falling back to copying. ${hint}")
+
+file(REMOVE_RECURSE "${link}")
+if(IS_DIRECTORY "${target}")
+    file(COPY "${target}/." DESTINATION "${link}")
+else()
+    file(COPY_FILE "${target}" "${link}" ONLY_IF_DIFFERENT)
+endif()