emulator: fix CCWA for PTS

emulator: fix CCWA for PTS

During test TP/TCA/BV-05-I [Terminate Ongoing Call – While Call Waiting]
PTS fails if multiple +CCWA are sent (waiting for 1st phone number when
waiting one becomes incoming, intead of 2nd phone number).
So, send only 1 +CCWA.

Update RING timer management to be started as soon as an incoming call
exists, and retrieve +CLIP info for incoming or waiting call (in case
of waiting call becoming incoming call, call indicator changes before
internal call status is updated)

Force to send +CCWA (if needed) on reception of AT+CCWA=1