[UWP] Support Windows 10 1809 LTSC

[YZahringer]

🔙 Regression

We can not use the latest version 2.1.0 with UWP targeting Windows 10 1809.
The version 1809 is an LTSC version, supported until 2029 and Xamarin.Forms support it.

This is the commit that make the regression, without any breaking change announcement or issue to track it 😕
0645bd6#diff-74eaa5dcbcc57fd0aa109ed278deb4132b29340aff41b89a15c386ca87479f43

Related: #723, #712, #707

Old (and correct) behavior

Windows 10 1809 and later supported

Current behavior

Only Windows 10 1903 and later supported

Reproduction steps

Use an UWP project with min version 1809.

Configuration

Version: 2.1.0.0

Platform:

• 📱 iOS
• 🤖 Android
• 🏁 WPF
• 🌎 UWP
• 🍎 MacOS
• 📺 tvOS
• 🐒 Xamarin.Forms

[martijn00]

Visual Studio 2022 doesn't support target 10.0.17763.0 anymore. I need to be able to build the code to release it.