* 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>