[P054] Allow GPIO configuration for ESP32 units

[tonhuisman]

From a forum request

Features:

• Allow GPIO selection on ESP32 units (not forced to GPIO 2 like on ESP8266)
• Formatted source
• Use Direct-GPIO library for more accurate timing when sending the break/comm start signal
• Use ESPEasySerial library to allow flexible GPIO configuration on ESP32

TODO:

• Testing (confirmed)
• Add documentation