Fix polygons not clearing (open-navigation#72)

* Add behavior tree to navigate to start before starting fields navigation

* snake case

* comments

* rviz visualization for demo

* Update rviz_config.rviz

* Linting and add to other demo

* Fix polygons not clearing, credit to tonynajjar

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Co-authored-by: Marc Morcos <30278842+MarcM0@users.noreply.github.com>

opennav_coverage_bt/src/compute_complete_coverage_path.cpp

@@ -46,6 +46,7 @@ void ComputeCoveragePathAction::on_tick()
     // Convert from vector of Polygons to coverage sp. message
     std::vector<geometry_msgs::msg::Polygon> polys;
     getInput("polygons", polys);
+    goal_.polygons.clear();
     goal_.polygons.resize(polys.size());
     for (unsigned int i = 0; i != polys.size(); i++) {
       for (unsigned int j = 0; j != polys[i].points.size(); j++) {