Add support to gRPC call

[mcruzdev]

Context

The Serverless Workflow specification says:

gRPC: Supports Remote Procedure Call (RPC) using gRPC, a high-performance, open-source universal RPC framework. This is suitable for connecting to services that require low-latency and high-throughput communication.

The gRPC is a default function that MUST be supported by all implementations and runtimes.

Proposal

To add support to gRPC function to sdk-java implementation. More information about gRPC here.