track: add g-i annotation that ges_track_new() takes ownership of caps passed
track: add g-i annotation that ges_track_new() takes ownership of caps passed

cfoch/ges,volodymyrrudyi/gst-editing-services,cfoch/ges,pitivi/gst-editing-services,cfoch/gst-editing-services,cfoch/ges,cfoch/gst-editing-services,cfoch/ges,pitivi/gst-editing-services,volodymyrrudyi/gst-editing-services,pitivi/gst-editing-services,cfoch/gst-editing-services,volodymyrrudyi/gst-editing-services,cfoch/gst-editing-services,pitivi/gst-editing-services