Remove IAvaloniaPropertyVisitor due to generic virtual methods.

[grokys]

What does the pull request do?

Removes IAvaloniaPropertyVisitor which was based around using generic virtual methods, which we're trying to remove. It was only used internally in creating ISetterInstances so adds a virtual method to AvaloniaProperty to do this explicitly without generic virtual methods.

This PR includes the changes from #8021 so until that is merged you can see the changes specific to this PR in the commit Remove IAvaloniaPropertyVisitor.

[avaloniaui-team]

You can test this PR using the following package version. 0.10.999-cibuild0020067-beta. (feed url: https://nuget.avaloniaui.net/repository/avalonia-all/index.json) [PRBUILDID]

[avaloniaui-team]

You can test this PR using the following package version. 0.10.999-cibuild0020071-beta. (feed url: https://nuget.avaloniaui.net/repository/avalonia-all/index.json) [PRBUILDID]

[grokys]

Benchmarks as compared with #7980 and filtered for noise:

| Faster                                                                           | base/diff | Base Median (ns) | Diff Median (ns) | Modality  |
| -------------------------------------------------------------------------------- | ---------:| ----------------:| ----------------:| ---------- |
| Avalonia.Benchmarks.Layout.ControlsBenchmark.CreateTextBox                       |      2.10 |       2782200.00 |       1325559.18 | multimodal|

Only one benchmark has changed, but it's 2x faster.