Revisit gRPC design for new service typing syntax

[daneshk]

Description
Migrate current gRPC service implementation to new service typing syntax

Design
https://docs.google.com/document/d/1UDPm9bRZ9DS97W5tvZOnolYQsohKYLXLAfrofQJXitI/edit#

Subtasks

*** Server Side ***

• Return a non-streaming response from a remote function
• Return a streaming response from a remote function
• Update sendError API to accept Ballerina Error type
• Change encode/decode logic to handle langlib data types
• Add support to send/receive custom headers in the request/response path
• Enable Call Security(authentication and authorization)

*** Client Side ***

• Support Synchronous Client
• Remove support for Asynchronous client
• Add support to send/receive custom headers in the request/response path
• Enable Call Security(authentication and authorization)

*** Protobuf Tool ***

• Generate custom caller object from the protobuf tool
• Generate custom Streaming Client from the protobuf tool
• Update protobuf tool to generate specific types using langlib data types

Post Alpha

• Update compiler plugin to validate new service syntax

[daneshk]

Drafted Document: https://docs.google.com/document/d/1UDPm9bRZ9DS97W5tvZOnolYQsohKYLXLAfrofQJXitI/edit#