Make ComboBox dropdown respect scale transform

[grokys]

What does the pull request do?

Fixes #7147 by making ComboBox's dropdown respect the ComboBox scale transform.

• Adds a Popup.InheritsTransform property
• Sets this to true in the ComboBox template(s)
• Adds a Transform property to PopupRoot and OverlayPopupHost
• Adds a LayoutTransformControl to PopupRoot and OverlayPopupHost's template, with its transform bound to this Transform property
• Applies transform from the Popup placement target to the PopupRoot.Transform/OverlayPopupHost.Transformproperty whenInheritsTransform` is set
• Applies the transform also to the PopupRoot/OverlayPopupHost's min/max/width/height setting
  • In order to do this, the rather hacky BindConstraints method was removed from IPopupHost and the relevant properties were instead added to the interface and set from Popup

Note that only scale transforms are currently handled correctly; rotate transforms are not handled correctly. This is because our popup positioning API (which comes from Wayland) makes applying rotate transforms rather difficult as the popup position is based on a Rect on the parent window. It will probably be possible to correctly handle rotate transforms here, but should probably be done in a separate PR if anyone fancies tackling it - as it may be tricky.

Breaking Changes

Changes the API of the IPopupHost interface.

Fixed issues

Fixes #7147

[avaloniaui-team]

You can test this PR using the following package version. 0.10.999-cibuild0020112-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-cibuild0020232-beta. (feed url: https://nuget.avaloniaui.net/repository/avalonia-all/index.json) [PRBUILDID]