Provide convenience functions for reading and writing characteristics

[nkolban]

While studying BLE Noble, I found the existence of convenience functions in that library. What a great idea!! The following are candidates for conveniences in this library:

BLEDevice::write(bdAddress, serviceUuid, characteristicUuid, value)
value BLEDevice::read(bdAddress, serviceUuid, characteristicUuid)
BLEClient::write(serviceUuid, characteristicUuid, value)
value BLEClient::read(serviceUuid, characteristicUuid)
BLERemoteService::write(characteristicUuid, value)
value BLERemoteService::read(characteristicUuid)

[nkolban]

Easiest ones now implemented:

BLERemoteService::setValue(BLEUUID characteristicUuid, std::string value)
std::string BLERemoteService::getValue(BLEUUID characteristicUuid);

[nkolban]

We have now added:

BLEClient::setValue(BLEUUID serviceUUID, BLEUUID characteristicUuid, std::string value)
std::string BLEClient::getValue(BLEUUID serviceUUID, BLEUUID characteristicUuid)

BLEDevice::setValue(BLEAddress bdAddress, BLEUUID serviceUUID, BLEUUID characteristicUuid, std::string value)
std::string BLEDevice::getValue(BLEAddress bdAddress, BLEUUID serviceUUID, BLEUUID characteristicUuid)

Coding is now likely to be complete but testing needs performed. We can be loose on testing as the changes affect only new code and not existing.

[VDelport]

Thank you for your great project. :)
Would you please add getValue and setValue functions for BLEDevice that can be used to read or write byte arrays?

[chegewara]

https://github.com/nkolban/esp32-snippets/blob/master/cpp_utils/BLERemoteCharacteristic.h#L49
https://github.com/nkolban/esp32-snippets/blob/master/cpp_utils/BLERemoteCharacteristic.h#L53