v12 Regression: Moving OptionalFeatureProviderExtensions from Avalonia.Platform to Avalonia namespace breaks compatibility

[fitdev]

Describe the bug

As part of #20589 OptionalFeatureProviderExtensions was moved from Avalonia.Platform namespace to Avalonia, which breaks binary compatibility with some well known libs like LiveCharts2 for example. This results in Type Load Exception at runtime.

To Reproduce

Try using LiveCharts2 with Avalonia 12.

Expected behavior

If at all possible OptionalFeatureProviderExtensions should remain in Avalonia.Platform or else be properly type-forwarded.

Avalonia version

12 Preview 1

OS

No response

Additional context

No response

[Gillibald]

V12 is introducing breaking changes. There is no guaranteed compatibility with V11.

[fitdev]

That's understandable. But still perhaps some minor namespacing changes may be avoided unless absolutely necessary.