Parametrize collision checking in the nav2_graceful_controller

[suchetanrs]

Feature request

Feature description

Hello!
In certain cases of my robot's navigation, I want pure path-following behaviour without any collision detection. However, I want to do this with the graceful_controller.
Can we provide optional collision checking in nav2_graceful_controller like how it is done in the docking_server.

[SteveMacenski]

Got it - sounds good!