WIP: Add support for bicolor led in the simulator

WIP: Add support for bicolor led in the simulator

I noticed that the bicolor led isn't supported in the simulator. Here is a quick mockup of how I would add support for it.

I added an SVG filter to the #light rectangle in the SVG which lets us multiply the colours by a matrix in code. I then insert values so that the original green colour gets mixed into the combination of red and green requested by `watch_set_led_color`

# Testing
So far I've only tested this with the standard firmware build but it seems to work.

# Possible issues
I wasn't 100% sure what to do when red + green > 255, current behaviour is that it gets clamped to 255 in the simulator.