I'm trying to create a my own custom bt plugin. In the official tutorial https://navigation.ros.org/plugin_tutorials/docs/writing_new_bt_plugin.html, I can't see an instruction or an example on how to create a behavior tree plugin in a separate ros2 package just like in this nav2 repo tutorial https://github.com/ros-planning/navigation2_tutorials/tree/master where the custom plugins (custom costmap, behavior, controller and planner) are created in a separate package.
So I'm wondering, is it possible to create the bt plugin/node in a separate package? or I need to install nav2 from source and try to create the bt plugin on the /navigation2/nav2_behavior_tree/plugins folder?