Add register-backed components

[SteveDesmond-ca]

#2 provides components where all pins are directly mapped to inputs on the component. To reduce wiring to the device for some components, shift registers can be used.

• 7-segment display
• LED matrix

This could be done as a distinct class from the direct one, abstracting a common base class with 2 implementation, or perhaps use a strategy pattern to call an internal implementation. Regardless, the public API should be consistent between both.