Enhance cleos to enable new RPC send_transaction

[b1aafulei]

Change Description

With regard to issue #7536, enhance cleos so as to enable send_transaction, an RPC newly introduced in EOSIO v1.8.

Changes are made to programs/cleos/main.cpp and programs/cleos/httpc.hpp.

Background

• For versions v1.8 or after, both RPC send_transaction and push_transaction are supported.
• For versions before v1.8, only RPC push_transaction is supported.
• RPC send_transaction and push_transaction are almost the same, except the traces they return, which can be viewed in JSON format by adding a -j option in the command calling them.

Flow Control

• Users can enforce always using old RPC push_transaction by adding a flag --use-old-rpc.
• Otherwise, which RPC will be called depends on the current nodeos version:
  • If the nodeos version is between v1.0 and v1.7, call old RPC push_transaction;
  • Otherwise, call new RPC send_transaction.

Test

Have tested behavior such as create account, issue and transfer for nodeos version v1.8.0 and version v1.7.4.

Sidenote

In programs/cleos/main.cpp there is a void send_transaction(...) function, which, according to @arhag in issue #7536, is simply unrelated to this topic. Just ignore it.

Consensus Changes

• Consensus Changes

API Changes

• API Changes

Documentation Additions

• Documentation Additions

[b1aafulei]

I have modified the code adopting @arhag 's suggestion. Now the new flow is

Flow

• Users can enforce using old RPC push_transaction by adding a flag --use-old-rpc.
• Otherwise, without such a flag, cleos will always call the new RPC send_transaction.
  • If it happens that the call to send_transaction fails, an error message will be printed out, saying that the new RPC may not be supported, and suggesting the user add the flag --use-old-rpc to call push_transaction instead.