[FEATURE] Add support for APDS9960 clones

[nicknugget]

Add support for more than one chip id and improve chip detection to initialize clones properly.

Adafruit_APDS9960.h: Use defines to define more than one chip id and make handling of these easier.

Adafruit_APDS9960.cpp: Improve chip detection part in Adafruit_APDS9960::begin() to handle more than one chip id and allow clones with different id than the genuine chip to be used without a failing initialization.

Should work with every platform and shouldn't break any existing code as the changes are minor ones.

Tested with a Chinese clone of the APDS9960 without problems.