Memory leak in QuicStream + multiprocessing of already processed data

[AntiTenzor]

Describe the bug

1. Internal member _data of this class only grows in size.

2. Also because of this, the property Data grows in size also and returns
   already processed data again and again.

Expected behavior
When full pack of data is received, it have to be reported with help of event
OnStreamDataReceived and after that internal buffer _data have to be cleared.

Additional context
Correct behavior is a little bit tricky to implement.
As far as I understand your implementation,
some internal method signatures should be adjusted.

For example, QuicConnection.ProcessFrames
should be
ProcessFrames(List<Frame> frames, out byte[] fullPacket)

and QuicConnection.OnStreamFrame
should be
OnStreamFrame(Frame frame, out byte[] fullPacket)

also QuicStream.ProcessData
should become
internal void ProcessData(StreamFrame frame, out byte[] fullPacket)