Implement graph serialization / structure under Bolt protocol

[gitbuda]

https://neo4j.com/docs/bolt/current/bolt/structure-semantics/ -> the graph/subgraph is missing.

Equivalent to path, but encoding multiple "paths" essentially minimizing the network traffic because the user only needs info about the whole graph.

The question is, how does the engine know that it's ok to serialize something into a graph? Most likely, a Graph data type on the query engine side is enough (the user would have to "collect" vertices|edges|paths into a graph).