[CEN-651] Generate global api id in protoc-gen-orion

[jason-xxl]

This change is the first step to maintain a global API id scheme, which can be in future used to aggregate all reliability related information in backend world.

example output in a generated .proto.orion.pb.go file,

// Global ID of each API

/* "0cbb7024" -> "ChatService.ReceiveMessage" "0a8abe73" -> "ChatService.InitSendImages" "f0e121c0" -> "ChatService.SendImages" */

// Encoders

// Handlers

// Decoders

// Streams

https://carousell.atlassian.net/wiki/spaces/CT/pages/348127890/Proposal+Global+Error+Code+Scheme