Expand node_secure_root using local_namespace (#300)
Expand node_secure_root using local_namespace (#300)

* Expand node_secure_root using local_namespace

* rcutils_normalize_path -> rcutils_to_native_path

* correct comments and docblock

* node_root_norm -> node_root_path

* normalized -> native

* Adding TODOs for function reuse

* Adding Null check node_secure_root

* Adding override for ROS_SECURITY_NODE_DIRECTORY
Addressing https://github.com/ros2/sros2/issues/69

* Change from strcpy to memcpy

Signed-off-by: Ruffin White <a5dcd3926c81eb1ee3adbb93ba7dae191323a4e0@gmail.org>
ros2/rcl,ros2/rcl