eth: add traceCallBlock method

[s1na]

It hasn't been tested much. There's much room for improvement
e.g.:

> debug.traceCallBlock({number: '0x20', transactions: [{from: eth.accounts[0], value:"0x1", gasPrice: "0xffffffff", gas: "0xffff", input: "0x43"}]}, "latest")[0].result
{
  failed: false,
  gas: 53018,
  returnValue: "",
  structLogs: [{
      depth: 1,
      gas: 12519,
      gasCost: 2,
      op: "NUMBER",
      pc: 0,
      stack: []
  }, {
      depth: 1,
      gas: 12517,
      gasCost: 0,
      op: "STOP",
      pc: 1,
      stack: ["0x20"]
  }]
}

[s1na]

Closing in favour of #25743