AvaloniaUI 12.0.0 support

[fntc]

Describe the bug
Avalonia will release their 12.0.0 Release candidate this week. I am creating this bug to track API incompatibilities.

To Reproduce
Reference Avalonia 12.0.0-preview2 (or RC once it is available)

Expected behavior
App with LiveCharts2 runs as expected.

https://docs.avaloniaui.net/docs/avalonia12-breaking-changes

[fntc]

Stacktrace on Startup (Windows):

Unhandled exception. System.MissingFieldException: Field not found: 'Avalonia.Input.Gestures.PinchEvent'.
at LiveChartsGeneratedCode.SourceGenCartesianChart..ctor()
at LiveChartsGeneratedCode.SourceGenCartesianChart..ctor()
at LiveChartsCore.SkiaSharpView.Avalonia.CartesianChart..ctor()

Stacktrace on Startup (Android):

03-17 11:39:14.390 E/AndroidRuntime(17740): android.runtime.JavaProxyThrowable: [System.MissingFieldException]: Field not found: 'Avalonia.Input.Gestures.PinchEvent'.
03-17 11:39:14.390 E/AndroidRuntime(17740): at LiveChartsGeneratedCode.SourceGenCartesianChart..ctor(Unknown Source)
03-17 11:39:14.390 E/AndroidRuntime(17740): at LiveChartsCore.SkiaSharpView.Avalonia.CartesianChart..ctor + 0x0(Unknown Source)

[beto-rodriguez]

WIP #2121