feat: allow to decode array length only as number using decodeData

[CJ42]

What kind of change does this PR introduce (bug fix, feature, docs update, ...)?

⭐ Feature

What is the current behaviour (you can also link to an open issue here)?

When using decodeData with key type Array, only arrays [ ... ] can be returned.

What is the new behaviour (if this is a feature change)?

Allow to use decodeData with key type Array that allows to pass a a 16 bytes long value, that will be decoded as a number.

const decodedData = ERC725.decodeData(
      {
        keyName: 'LSP12IssuedAssets[]',
        value: '0x00000000000000000000000000000003',
      },
      [
        {
          name: 'LSP12IssuedAssets[]',
          key: '0x7c8c3416d6cda87cd42c71ea1843df28ac4850354f988d55ee2eaa47b6dc05cd',
          keyType: 'Array',
          valueContent: 'Address',
          valueType: 'address',
        },
      ],
    );

will output:

// decodedData {
//  key: '0x7c8c3416d6cda87cd42c71ea1843df28ac4850354f988d55ee2eaa47b6dc05cd',
//  name: 'LSP12IssuedAssets[]',
//  value: 3
// }

Other information: