Add Clock Multiplier & Divider

[chrisib]

One last MR for 2023!

Adds a combined clock multiplier & divider script. Pretty standard functionality; each output can have an independently-controlled modifier from [/12, /8, /6, /5, /4, /3, /2, x1, x2, x3, x4, x5, x6, x8, x12]. DIN accepts the incoming clock signal, which cannot be slower than 1Hz. AIN accepts a digital reset signal.

Each output is a ~50% duty cycle square wave with a rate equal to the incoming clock speed multiplied by the clock modifier.

This script uses the same analog-to-digital input wrapper introduced in #311 to allow AIN to be used in a fashion similar to DIN with a callback on the rising and falling edges.

[chrisib]

Rebased to latest traffic branch after rebasing that to latest main.