add XFN ON/OFF/STATUS commands via xfn_status_handler_cb
XFN ON/OFF/STATUS provide a simple way to enable and disable
the plugin without unloading it.
xfn_status_handler_cb handles the 3 commands.
status only gives a message to the user about the current state
of the plugin.
add XFN_DPM ON/OFF/STATUS commands via xfn_dpm_status_handler_cb
XFN_DPM ON/OFF/STATUS provide a way to enable and disable
messages content visibility on notifications.
xfn_dpm_status_handler handles the 3 commands
status only gives a message to the user about the current state
of the visibility.