Arduino Bluetooth scanner: How to list bluetooth devices with HC-05

A scanner which lists nearby Bluetooth devices and reports the list to AWS IoT service. This project was a bit tricky because I had a hard time finding full information. Many tutorials described how to set HC-05 in AT-mode but they didn&mention that there are actually two different AT-modes and only the full AT-mode enables to correctly run AT+INQ command. Otherwise, it was really simple to just connect 3.3V regulator, HC-05 module, ESP8266 and 3.3V Arduino Pro Mini (no level shifting required!). If you want to use 5V Arduino then level shifting (5V to 3.3V) is required between Arduino&TX pins and other modules RX pins (HC-05 and ESP8266). Also, HC-05 pin 34 should be connected to 3.3V (regulator or level shifter).