Previously the combinator state was lost when traversing nested selectors. To fix it, instead of running the parent selector in `NestingSelector.Evaluate`, return the parent selector with `MovePrevious`. This required `MovePrevious` to be aware of parent styles and because I had to change its signature, I also made it internal as it doesn't need to be a public API.
Exposed by the previous fix for #8372: re-entrancy in `PropertySetterInstance.Dispose()` is causing detaching a style to call `ClearValue` on the property. Previously this wasn't a problem as `ClearValue` didn't work, but now it is.
(Also added one passing test which tests the same scenario in `PropertySetterBindingInstance` for future coverage)
* Merge core libraries.
Everything below `Avalonia.Controls` into `Avalonia.Base`.
* Move new files to correct place.
* Removed unused dirs/projects,
* Removed outdated references from theme assemblies.
* Merge unit tests to match new assembly layout.
* Fixup test namespaces.
* Make directory match namespace.
* Move files to match namespace.
* Move files to match namespace.
* Fix up incorrect namespace.
`Avalonia.Visuals.Media.Imaging` -> `Avalonia.Media.Imaging`.
* Fix resource URL.
* Removed outdated dependencies.
* Added missing project reference.
* Update test namespaces.
* Fix merge error.
* Fix merge errors.
* Fix bad merge in WindowsInteropTest.csproj.
* Fix up merge errors in csprojs.
* Remove merged tests from nuke.
* Fix up namespace.
* Fix compile error.
* Fix failing tests.
Now that more unit tests are present in Avalonia.Base.UnitTests, general `AvaloniaObject` properties are getting registered. Ignore those.
Co-authored-by: Jumar Macato <16554748+jmacato@users.noreply.github.com>