Support SRT listener mode.

[shogo4405]

Description & motivation

• Supported SRT Listener mode.
• Only one connection is supported. By configuring as follows, you can wait as a listener to receive and play a stream from another client.

connection = SRTConnection()

stream = SRTStream(connection: connection)
stream.play()

view.attachStream(stream)
connection.open(URL(string: "srt://0.0.0.0:9998"), mode: .listener)

Type of change

• New feature (non-breaking change which adds functionality)

Screenshots: