Make Context and Execution.Node accessible via Receiver parameter

[stuebingerb]

aPureBase/KGraphQL#145

[stuebingerb]

One downside of this approach:

Currently, one can specify the expected execution class in the resolver arguments:

resolver { myParam: String, node: Execution.Node -> ... }
resolver { myParam: String, node: Execution.Remote -> ... }
resolver { myParam: String, node: Execution.Fragment -> ... }

With an ExecutionScope we most likely can only provide a node: Execution (the base class), requiring resolvers to deal with all possible sub classes.