Started laying foundations for the block sensor

As usual, I started with the block classes and block entity for the sensor, and the definitions, then will move on to the actual logic.

The basic setup was pretty simple, but this sensor will be my first one with a variable redstone output based on the distance of the detected block. Instead of just turning on or off, the redstone strength will change depending on how close the detected block is to the sensor.

Still have some more logic and testing to do, but the basic foundation is now in place.