Add support for connecting using standard Arduino client abstraction

[proppy]

Either using:
https://github.com/arduino-libraries/ArduinoHttpClient
Or directly:
https://www.arduino.cc/en/Reference/ClientConstructor

Instead of the HttpClient from the esp8266 core.

That would allow us to support for more boards, and that's what other libraries have been doing:
https://github.com/adafruit/Adafruit_IO_Arduino/