v0.2.0 Non-Subscription operations, Infinite timeout duration, Improved error handling.

Description

Changes made to improve stabilities and capabilities in terms of features and security

Renamed Proxy to OverEngine.
Added multiple new message types for error and output handling for Envoy and OverEngine.
Added throughout recover for error handling for both future and stream results.
Updated OperationMessage, Added GqlError for proper error formats.
Added capabilities to respond to non-streaming operation using GraphImmediate and StatelessOp.
Updated OverEngine to be able to execute operation and pipe result back to self with proper error handling.
Kill / Terminate connection on GraphException.
Moved onInit to wait after acknowledgement.
Updated timeoutDuration to allow Duration.Inf which will remove timeout.