test board: wire buttons to the analog inputs

[rusefi]

@mck1117 says "one idea I had for a test board I had: wire buttons to the analog inputs, and LEDs to outputs. Write firmware that just reads inputs and writes them to each output, That way you can just press buttons and make sure exactly one LED turns on."

we have the outputs. We have JLC soldering switches for us. I think that's a great idea!!!