Partial classes weren't providing any benefit and were hindering testing. Code is a lot simpler without them

Involved a bit of rework to add more interfaces for testability

Tests cover Constructor, Properties, Initialize, Read methods.
Todo: Write methods, Interrupts

This in theory should work, but I'm still having trouble getting the device to respond. Will come back to this once interrupts are working with I2C

- Use "edgefalling" instead of "edgerising" for interrupt. (Default configured setting for device)
- Inputports now have their initial values set
- Whole lot of logging added
- Interrupt ports do work, but only once

- Any interrupt mode can be used now, as long as the same mode is used for all interrupt ports.
- Interrupt handling for `McpDigitalInputPort`s now alerts if the pin is interrupted or if the pin's value does not match last state. This compensates for missed interrupts a lot more consistently.
- Logging is now limited to init and port creation, which is where most important things happen anyway.
  - Also Logging SPI activity, but this a is bit more careful so as to not slow down with logging when it isnt needed.
- Logging is now done via `McpLogger` static class, which has methods to enable/disable and change the output destination of logging. By default logging is disabled.