this adds an option NO_UNDEFINED_SYMBOLS to the rclcpp_components_register_node cmake macro, which adds the required linker option to the (component library) target to deny undefined symbols.

Undefined symbols usually produce an error if an executable is built, but due to the way the autogenerated executable generated by rclcpp_components_register_node is constructed, that doesn't happen here, and the error occurs only when executing it.
This change makes this a link-time error again.

This is especially intended for the workflow of migrating a ros node which was built directly as an executable before to using rclcpp_components_register_node.

By default, the option is disabled. If no adverse impact is detected, i suggest enabling it by default in a future release.

fixes #2744