Refactor network layer to use streams

Summary:
The network layer now has a `Session` that handles all things that should be
done before the `Execute` method is called on sessions. Also, all sessions
now communicate using streams instead of holding the input buffer and writing
to the `Socket`. This design will allow implementation of a SSL middleware.

Reviewers: buda, dgleich

Reviewed By: buda

Subscribers: pullbot

Differential Revision: https://phabricator.memgraph.io/D1314

tests/unit/bolt_chunked_decoder_buffer.cpp

@@ -7,7 +7,7 @@ uint8_t data[SIZE];
 
 using BufferT = communication::bolt::Buffer<>;
 using StreamBufferT = io::network::StreamBuffer;
-using DecoderBufferT = communication::bolt::ChunkedDecoderBuffer;
+using DecoderBufferT = communication::bolt::ChunkedDecoderBuffer<BufferT>;
 using ChunkStateT = communication::bolt::ChunkState;
 
 TEST(BoltBuffer, CorrectChunk) {