Need to have an API to send ReInvite with "sendonly" in SDP

[jimmyxu1985]

Currently the reconnectMedia will only send ReInvite with "sendrecv" in SDP, but if the call is on hold, we cannot use reconnectMedia API to recover it since if client send ReInvite with "sendrecv", call will resume.

But if we don't send ReInvite at all when call is on hold, if other party hangup call, client cannot receive the BYE from server.

So we need to add an API or exten reconnectMedia API to send out ReInvite with "sendonly" so that we can keep the hold state and also we can receive BYE from server.

Related to bug ticket: FIJI-29843

[tylerlong]

But if we don't send ReInvite at all when call is on hold, if other party hangup call, client cannot receive the BYE from server.

As I tested, when the call is on hold, if other party hangup call, phone client CAN receive the BYE from server. However, there is about 5 seconds delay. I mean the BYE message is received 5 seconds after the other party hangup.