Use codec registry to make a list of supported media codecs instead of hardcoding it

[alula]

koe/core/src/main/java/moe/kyokobot/koe/gateway/VoiceGatewayV4Connection.java

Lines 28 to 33 in 089b4f7

	SUPPORTED_CODECS.add(new JsonObject()
	.add("name", "opus")
	.add("type", "audio")
	.add("priority", 1000)
	.add("payload_type", 120));
	}