The current implementation only send the +CIEV:<call>,<active> event
if there's an active modem in ModemManager. This may lead to headset
disconnection as in (1) if the profile is by another application than
telephony one, e.g. a conference application/website.
This commit improves dummy call status update by adding a new
"bluez5.disable-dummy-call" props param in bluez5 device, allowing
external application like WirePlumber to set it dynamically.
(1) https://gitlab.freedesktop.org/pipewire/pipewire/-/issues/1744
Fixes: https://gitlab.freedesktop.org/pipewire/pipewire/-/merge_requests/2606
