Add details on why trimming is incompatible with WinForms and WPF applications

We’re using a aka.ms links, https://aka.ms/dotnet-illink/windows-forms and https://aka.ms/dotnet-illink/wpf, to point developers to know more about dangers on trimming with WinForms and WPF applications. It currently points to the main doc [trimming ](https://docs.microsoft.com/en-us/dotnet/core/deploying/trim-self-contained) page. That page has a brief description of WinForms and WPF applications being incompatible with trimming but it will be good to have a separate pages to address this.

(gewarren added doc details below)

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#### Document Details

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* ID: a1a6f297-c659-3770-42d9-d277895b5d25
* Version Independent ID: 3061aedd-2264-90da-b244-b8ed7bf416fc
* Content: [Trim self-contained applications - .NET](https://docs.microsoft.com/en-us/dotnet/core/deploying/trim-self-contained)
* Content Source: [docs/core/deploying/trim-self-contained.md](https://github.com/dotnet/docs/blob/main/docs/core/deploying/trim-self-contained.md)
* Product: **dotnet-fundamentals**
* GitHub Login: @jamshedd
* Microsoft Alias: **jamshedd**