Neo4j channel adapters & gateways support

[markusherbert]

Expected Behavior
There should be support for Reactive and non Reactive code (with .block()). Neo4j also mostly prefers bulk operations, therefore there should be native support for this (Reactively with .block()). We should use Spring Data Neo4j.

Current Behavior
No native support

Context
I try to map here all the most needed but missing components.
This arcticle can be super helpful. Also referenced from here.

[corneil]

We should also consider cases where we provide Cypher that can be parameterized and the output is a graph or JSON or mapped using a mapper that creates the required objects.

[artembilan]

I think whatever is available for us in Spring Data Neo4J is OK.