Reduce code duplication in action find

[vitorfhc]

Reduce code duplication in action find

Description:

Everytime a command or subcommand is trying to find the right run function it runs this same code:

if (argc >= 3) {
    std::string command{argv[2]};
    auto it = commands.find(command);
    if (it != commands.end())
      return commands[command](argc, argv, out, err);
}

This could be avoided by creating a function responsible for that.
This is now happening at cptools.cpp only, but polygon pull/push subcommand will have the same code.