Build visual Feedback with LEDs

[felixherbst]

8 WS2812b LEDs can be used to display the current status. Some visualization ideas:

-show the current fan speed in 8 steps, only when the user is actually turning the knob plus some seconds after the interaction
-startup animation while booting or searching for wifi, maybe a ping pong animation
-status codes, like orange blinking during wifi setup

What needs to be done:
-setup the LEDs and define start state
-implement one ore more visualizations

Technical information:
On the CleanAirPCB v1, 8 WS2812b LEDs are connected to IO18 and succesfully tested with the Adafruit NeoPixel Library.