[Bug] ROS2 Foxy build failing

[shreyasgokhale]

Due to updates in Navigation2 and Foxy, the build fails for plansys2_patrol_navigation_example and plansys2_bt_example package at multiple stages. This causes the example not to launch / launch incorrectly.

1. Conflicting data types.

   --- stderr: plansys2_bt_example                               
   In file included from /home/ubuntu-foxy/plansys_ws/src/ros2_planning_system_examples/plansys2_bt_example/src/behavior_tree_nodes/Move.cpp:18:
   /home/ubuntu-foxy/plansys_ws/src/ros2_planning_system_examples/plansys2_bt_example/include/plansys2_bt_example/behavior_tree_nodes/Move.hpp:38:8: error: conflicting return type specified for ‘virtual void plansys2_bt_example::Move::on_success()’
   38 |   void on_success() override;
     |        ^~~~~~~~~~
   In file included from /home/ubuntu-foxy/plansys_ws/src/ros2_planning_system_examples/plansys2_bt_example/include/plansys2_bt_example/behavior_tree_nodes/Move.hpp:23,
                from /home/ubuntu-foxy/plansys_ws/src/ros2_planning_system_examples/plansys2_bt_example/src/behavior_tree_nodes/Move.cpp:18:
   /home/ubuntu-foxy/plansys_ws/install/plansys2_executor/include/plansys2_executor/BTActionNode.hpp:105:26: note: overridden function is ‘BT::NodeStatus plansys2::BtActionNode<ActionT>::on_success() [with ActionT = nav2_msgs::action::NavigateToPose]’
   105 |   virtual BT::NodeStatus on_success()
     |                          ^~~~~~~~~~
   make[2]: *** [CMakeFiles/plansys2_bt_example.dir/build.make:89: CMakeFiles/plansys2_bt_example.dir/src/behavior_tree_nodes/Move.cpp.o] Error 1
   make[1]: *** [CMakeFiles/Makefile2:115: CMakeFiles/plansys2_bt_example.dir/all] Error 2
   make: *** [Makefile:141: all] Error 2
   ---
   Failed   <<< plansys2_bt_example [5.55s, exited with code 2]

2. The change in how the root of behavior tree is accessed. (from tree.root_node to tree.rootNode())

3. Updates to nav2_params

[fmrico]

I think we can close this :)