Add new RPC methods

[jsdanielh]

• JsonRpcServer: Add method to get an accounts tree chunk
  • Add RPC method to get an accounts tree chunk: getAccountsTreeChunk. The method receives as string arguments the block hash on which the snapshot will be taken and the startPrefix of the accounts tree chunk. Then it returns an AccountsTreeChunk object.
• JsonRpcServer: Add new RPC method to get more transaction details
  • Add new RPC method (getTransactionByHash2) that returns more fields than the getTransactionByHash method. The added fields are:
    • toType
    • fromType
    • validityStartHeight
    • networkId
• Fix some formatting
  • Fix formatting of these files:
    • JsonRpcServer.js
    • TransactionDetails.js

Pull request checklist

• All tests pass. Demo project builds and runs.
• I have resolved any merge conflicts.

[sisou]

Why must this be a new method, if you are only adding fields? That is not a breaking change, is it?

[jeffesquivels]

It's not a breaking change as long as the client library/code supports it (there are de-serialization libraries that require extra configuration to ignore unknown fields or else they will throw and exception/error out). We can´t change custom client code that works this way (nor is our responsibility), but at least we should check and, if needed, fix this on the community provided libraries, but we didn't want to make this core-js change dependent on that (the idea is to update and release core-js first and then release a new version of the libraries to support the new RPC methods and to make sure they ignore unknown fields, but this second step may take some time).

For PoS we should make sure to release with some kind of versioning scheme that allows us to improve the API while retaining backward compatibility for people who can't update their clients/libraries at the same time as their nodes.