Namespace RPC endpoint and add new endpoints

[shuse2]

Description

Current RPC endpoint should be namespaced as below.

chain

• getBlockByID
• getBlocksByIDs
• getBlockByHeight
• getBlocksByHeightBetween
• getTransactionByID
• getTransactionsByIDs
• getLastBlock

system

• getNodeInfo
• getModuleMetadata

generation

• postTransaction
• getTransactionsFromPool
• getStatus (Rename from getForgingStatus)
• updateStatus (Rename from updateForgingStatus)

Motivation

For version 6, we should reconsider what new endpoints should added for the framework considering new features.
Also, the endpoint should be namespaced to allow more endpoints to be added in the future in organized manner

Acceptance Criteria

• Update unit tests
• Each namespace endpoints are in different files