Bluetooth: Use special function to send filter management index events

For sending Index Added, Index Removed, Unconfigured Index Added and
Unconfigured Index Removed managment events the new helper functions
allows taking into account if these events are enabled for a certain
management socket or not.

Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>