Use custom gRPC implementation with Helidon

[a-saksena]

As a Block Node developer
I want to replace Helidon's OOTB gRPC layer with our custom PBJ implementation
So that, I have greater control of the gRPC layer

Tasks

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1. Replace server subproject grpc.io gradle dependencies with PBJ's Helidon plugin
2. Remove protoc/PBJ Translator code
3. Re-implement grpc.io integration to align with the Helidon plugin types, etc
4. Test our 3 gRPC method types: Unary, Server Streaming, Bidirectional
5. Repair Block Node unit tests
6. Fix simulator to work with protoc types and remove PBJ types

[mattp-swirldslabs]

Created PBJ bug ticket to document an issue with Server Streaming integration where the PBJ framework immediately disconnects a client after they connect to receive a stream of block items.

[mattp-swirldslabs]

Created PBJ feature ticket to document framework gaps when clients cancel or close connections to the Block Node.