* Update GPIO library and samples to NRTs

* Simplify if checks

* Simplify if checks

* Update per feedback

* Fix code style with pragma

* Update NRT annotations

* Update Windows-specific NRT errors

* Remove null check

* Remove type constraint

* Remove null check

* Simplify NRT annotations

* Enable nullable for _pinModes

* Adding a comment to the pragma
Co-authored-by: NJose Perez Rodriguez <joperezr@microsoft.com>

Co-Authored-By: NJose Perez Rodriguez <joperezr@microsoft.com>

* Added solution with all the projects

Useful for global changes, i.e StyleCop or dependencies

* Add stylecop rules to project

Need workaround for an issue with GeneratePlatformNotSupportedAssembly

Put a comment on all rules that are enabled in dotnet core but not here.
Some rules are enabled here but not there.

* Fix all enabled rules in Core

* Use autogenerated instead of message suppression for Interop stuff

* Iot.Device.Bindings (the overall project) imports the base Directory.Props directly, so exclude for now

* Use #pragma warning disable instead of <autogenerated />

* Update SysFs naming

* Trying to trick file names

* Added the file names back

* Change PinValue to struct

Allows easier interop with raw data and enables us to extend with additional functionality. This will avoid having to add additional APIs for convenience and repeated typing of `PinValue == PinValue.High ? 1 :  0`.

Doesn't impact existing enum usage.

Sample usage:

``` C#
    class Program
    {
        static void Main(string[] args)
        {
            PinValue value = true;
            Console.WriteLine($"True is {value}");
            TestApi(0);
            Console.WriteLine($"Equality is {PinValue.High == true}");
        }

        public static void TestApi(PinValue value)
        {
            Console.WriteLine($"PinValue is {value}");
        }
    }
```

* Ok, so you can't switch a struct. :) Bonus now that you don't have to. There is no such thing as an invalid PinValue anymore.

* Added editconfig file

* Beginning of cleaning

* Added summaries and sorted

* Added callback summaries

* Fixed ordering and switch/case based on feedback

* Basic cleanup in GPIO files

* Basic comment cleanup in GPIO files

* Removed othing lingering words

* Another round of GPIO cleaning

* Removed a couple more words

* Added readonly and updated casing

* Better method grouping and synced constructor summaries

Adding Raspberry Pi Driver

Adding UnixI2cDevice Implementations

Adding Eventing methods to the Unix Driver for Gpio

* Moving Code to the new Api after the ApiReview

* PR Feedback

Change GpioDriver to be an interface and inital implementation of UnixDriver