https://github.com/ros-planning/navigation2/blob/main/nav2_bt_navigator/src/bt_navigator.cpp#L248 we hardcode it in Bt navigator, but then its use is parameterized for different potential values <ComputePathToPose goal="{goal}" path="{path}" planner_id="GridBased"/>

We should have the goal_blackboard_name be a BT nav parameter that defaults to goal for use. Conceivably, someone could want to change the goal names for multiple running around with more context so the BT Nav shouldn't assume that port/blackboard name when none of our BT nodes hardcode it.