Further refactor of `Configuration` · elixir-webrtc/ex_webrtc@6835193

test chromium SDP offer is functional and maintains tracks (ExWebRTC.PeerSDPTest)

test firefox SDP offer is functional and maintains tracks (ExWebRTC.PeerSDPTest)

test stop two and add one with different kind (ExWebRTC.RenegotiationTest)

test replace_track/3 correct sender id (ExWebRTC.PeerConnectionTest)

test negotiation needed is not fired when adding transceiver during negotiation (ExWebRTC.PeerConnectionTest)

test stop one and add two with switched kinds (ExWebRTC.RenegotiationTest)

test add and remove tracks in a loop (ExWebRTC.RenegotiationTest)

test finishes handshake in active mode (ExWebRTC.DTLSTransportTest)

test stop_transceiver/2 with renegotiation (ExWebRTC.PeerConnectionTest)

test stop_transceiver/2 before the first offer (ExWebRTC.PeerConnectionTest)

Provide feedback