add crude encoding of PSN chunks

internal/encoders/packet_header_chunk.go

@@ -0,0 +1,14 @@
+package encoders
+
+import "encoding/binary"
+
+func EncodePacketHeaderChunk(timestamp uint64, versionHigh uint8, versionLow uint8, frameId uint8, framePacketCount uint8) []byte {
+	packetHeader := make([]byte, 12)
+
+	binary.LittleEndian.PutUint64(packetHeader, timestamp)
+	packetHeader[8] = versionHigh
+	packetHeader[9] = versionLow
+	packetHeader[10] = frameId
+	packetHeader[11] = framePacketCount
+	return EncodeChunk(0x0000, packetHeader, false)
+}