Display decoded transaction data when signing

[crystalin]

When using sign we should display the transaction data like we do in createAndSendTx. Ex:

{
  specVersion: '0x000003e9',
  transactionVersion: '0x00000002',
  address: '0x1d73AccdA91F7C9062911598b8434944Fa114389',
  blockHash: '0x280335e10a1fee7cee287fdebc74b18669e8eb50a8fdb8e5206d3991df609e67',
  blockNumber: '0x0013ff16',
  era: '0x6701',
  genesisHash: '0x91bc6e169807aaa54802737e1c504b2577d4fafedd5a02c10293b1cd60e39527',
  method: '0x0300379bc89fe09359f2a1bff317b76baff7f169c9f613000064a7b3b6e00d',
  nonce: '0x00000000',
  signedExtensions: [
    'CheckSpecVersion',
    'CheckTxVersion',
    'CheckGenesis',
    'CheckMortality',
    'CheckNonce',
    'CheckWeight',
    'ChargeTransactionPayment'
  ],
  tip: '0x00000000000000000000000000000000',
  version: 4
}