Make getOperations consider multiple Transfer Asset

[Torres-ssf]

We must consider multiple Transfer Asset operations in the same TX.

There is a bug in how the getOperations function is assembling Transfer Asset operations for processed TXs:

Consider the following Transaction that simply transfers coins from 2 assets to 2 different wallets:

    const asset1 = '0x0101010101010101010101010101010101010101010101010101010101010101';
    const asset2 = '0x0202020202020202020202020202020202020202020202020202020202020202';

    const request = new ScriptTransactionRequest({
      gasLimit: 10_000,
      gasPrice: 1,
    });

    request.addCoinOutput(receiver1.address, 100, asset1);
    request.addCoinOutput(receiver2.address, 100, asset1);
    request.addCoinOutput(receiver2.address, 100, asset2);

    const tx = await adminWallet.sendTransaction(request);

This transaction should generate 2 Transfer Asset operations, one for each receiver.

e.g.

[
  {
    name: 'Transfer asset',
    // TX sender
    from: {
      ...
    },
    // Receiver 1
    to: {
      ...
    },
    assetsSent: [
      {
        assetId: '0x0101010101010101010101010101010101010101010101010101010101010101',
        amount: BN(100)
      }
    ]
  },
  {
    name: 'Transfer asset',
    // TX sender
    from: {
      ...
    },
    // Receiver 2
    to: {
      ...
    },
    assetsSent: [
      {
        assetId: '0x0101010101010101010101010101010101010101010101010101010101010101',
        amount: BN(100)
      },
      {
        assetId: '0x0202020202020202020202020202020202020202020202020202020202020202',
        amount: BN(100)
      }
    ]
  }
]

However, getOperations returns the operations array containing only one Transfer Asset operation, usually the one that is processed last by the addOperations helper.

[arboleya]

Completed via #1619.