ament_cmake_python: --symlink-install does not work correctly if node is renamed

I got an issue report on Turtle Nest ROS 2 package, notifying that --symlink-install option does not work correctly for packages that are built for C++ and Python, when a node is renamed.

Here is the full issue report: https://github.com/Jannkar/turtle_nest/issues/15

I believe this might an issue on `ament_cmake_python` side?

Example of node renaming:
```
# Install Python executables
install(PROGRAMS
${PROJECT_NAME}/python_node.py
DESTINATION lib/${PROJECT_NAME}
RENAME python_node
)
```