clean RequestCoreService.getRequestsByAddress data

RequestCoreService.getRequestsByAddress isn't complete yet, still need to clean the data, which consists of adding timestamp to each request

The original typescript can be found here so I imagine the python would be something like

for payee in eventsCorePayee:
    payee['_meta] = {
        'blockNumber': payee['blockNumber'],
        'timestamp': self._web3Single.getBlockTimestamp(payee['blockNumber']),
        'requestId': payee['returnValues']['requestId']
    }

# and same for eventsCorePayer

Not entirely sure what self._instanceRequestCore.getPastEvents() returns (dictionary or data structure)