Introduce a new API that can return a GstTypeFind * with helper functions and data set around buffer data. While at it, drop factory field from GstTypeFindBufHelper. While it was useful for logging, it was not passed through function arguments and keeping it for logging would require an additional API increasing the API surface and making it harder to use. Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/3296>