Behavior tree example with multiple planners/controllers/goal checkers

[SteveMacenski]

to show-case how to use it correctly, as a tutorial and also have this Bt included in nav2_bt_navigator xml set.

Maybe a docking subtree with changing controllers on if environment is "dynamic" and changing the goal checker tolerances by request (docking fine, general coarser). Change planning algorithm if the first fails. That should highlight all 3 changes and showcase how to use 1 as a recovery and the other 2 as specific application example changes. Or maybe if its a pick-up-and-drop-off-box. the pick up is fine because you know where the box is, but the drop-off is coarse resolution because its just a general area