Android Things driver for SunFounder PCA9685

[zugaldia]

This is still very experimental and a work in progress. Basically, because I haven't tried it on real hardware yet. However, the code is very similar to the hat from Adafruit that we already have so I'm confident it shouldn't be a big lift to make it work.

This time I'm adding it as a separate module because I'd like to push it to Maven Central for anyone to be able to use it, even if they don't use this project.

cc: @hsalameh