Consider moving handlers to `nsls2-detector-handlers` repo

[mrakitin]

All the handlers from https://github.com/NSLS-II-ISS/xas/blob/main/xas/handlers.py can all be moved to https://github.com/NSLS-II/nsls2-detector-handlers, as it was done before via NSLS-II/nsls2-detector-handlers#3. That way the configuration will be stored more centrally, and the handlers can be deployed easier to both the beamline side and the tiled side.