[Docs] Mapping (Xamarin.Essentials)/.NET MAUI Platform APIs to WinRT APIs

[agneszitte]

Description

The .NET MAUI documentation currently includes information on Platform APIs, which were formerly known as Essentials.
https://learn.microsoft.com/en-us/dotnet/maui/platform-integration/?view=net-maui-8.0
To aid developers transitioning from (Xamarin.Essentials)/.NET MAUI Platform APIs to WinRT APIs, a comprehensive guide is essential.
This guide should detail the API mappings, supported platforms, and necessary setup, and include practical usage examples.

Proposed content for this guide

1. API Mapping Guide

   • Develop a detailed correspondence table or list mapping each (Xamarin.Essentials)/.NET MAUI Platform APIs to the WinRT APIs counterpart.
   • Highlight differences in API functionality or any limitations.

2. Platform Support

   • Document the supported platforms for each of those.
   • Note any platforms that are no longer supported or have known issues as needed.

3. Setup Instructions

   • Provide detailed setup instructions for each platform to assist developers in transitioning their projects.

4. Usage Examples

   • Include samples & code examples showing how to utilize WinRT APIs to replace (Xamarin.Essentials)/.NET MAUI Platform functionalities.
   • Focus on common use cases previously handled by (Xamarin.Essentials)/.NET MAUI Platform functionalities.

cc @dansiegel, @jeromelaban