kmssctpserverrpc: Set port as an input/output parameter

When port number 0 is used, the free available port used to bind the socket
is returned as an output parameter.

Change-Id: If0d3a7ee5168f62661045a5aa0439eef525b6738
gstsctpserversrc: Emit notify signal to provide bounded port

Change-Id: I67a11b81528638911b1da607f908e8828bf6d57a
gstsctpserversrc: If no port number is provided use an available one

Change-Id: Icda67b85646598bb3e7dde00b77ee728de27add3
kmsmultichannelcontroller: Provide a callback mechanism to create SctP src elements

Change-Id: I4036bb41eef6be6ee70005457310b4c7b60fe30d
kmsplumberendpoint: Send request to create video channel when valve is added

Change-Id: If1351c02f60e20048592368a76ea3553d404fdc9
kmsplumberendpoint: Create a new sctpserversrc when it is requested

Change-Id: Ib9a59ec56c8776201218586d799f09b652941dd7
kmsplumberendpoint: Connect video sctpclientsink element to valve

Change-Id: I6e81bf42fb351695805c6e20397a1ac61af90f68
kmsplumberendpoint: Connect audio sctpclientsink element to valve

Change-Id: I1148e66acffae314a48570a857c1fc21aacdf58d