display: migrate hd44780 sample to driver

Nico Lastzka


The HD44780 lcd chip is supported as a sample application for a long time now in zephyr. I'd like
to have a proper driver for this chip including dts bindings.

So I started to play with it in the last few days and got it running with the exception of a
display driver api.

The existing APIs don't seem to fit and I wonder if it makes sense to provide just another api
like for the microbit and grove displays.