TODO the GPIO module is gone. It needs to be re-implemented.
TODO need to document how a user should configure pads. The default
pad configurations are gone, so users who want to stay compatible
will need to provide the configurations themselves.

Much fewer macros, much easier to read, and nearly the same interface.

I'm adding these to the repo so that it's easier to review. We'll
talk about if we should continue maintaining in this repo, or in
a separate repo.

For my reference: the imxrt-iomuxc files track to commit d886fa4
in my local development repo.

The build-hal job will catch all formatting and lint errors when
checking the HAL. We just need to run the tests separately.