Fix ChunkDataCodec/ChunkBulkDataCodec

- Allow Network to iterate message queue even if session isn't available.
  This is important, we need to show the GUI for disconnect/kick if the
  server sends it to us and by the time we get it, session will be
  deactivated.
- Override isAsync in ChannelMessage (cause all messages are *technically*
  async)

Signed-off-by: Chris Sanders <zidane@outlook.com>