Previously, the number of action map subactions was limited to two per action (identified by user_path0, user_path1), however for devices with more than two user paths (e.g. Vive Tracker) it will be useful to support a variable amount instead. For example, a single pose action could then be used to query the positions of all connected trackers, with each tracker having its own subaction tracking space. NOTE: This introduces breaking changes for the XR Python API as follows: - XrActionMapItem: The new `user_paths` collection property replaces the `user_path0`/`user_path1` properties. - XrActionMapBinding: The new `component_paths` collection property replaces the `component_path0`/`component_path1` properties. Reviewed By: Severin Differential Revision: https://developer.blender.org/D13949