Merge branches 'tree-state-bmpbundle' and 'imglist-scalefactor'

Refactor wxImageList and convert it to use physical pixels and
add support for high DPI state images wxTreeCtrl using the new
wxImageList.

See #24000, #24033.

docs/changes.txt

@@ -77,6 +77,11 @@ Changes in behaviour not resulting in compilation errors
   called any longer by default, you need to explicitly enable 3.0 compatibility
   or change your code to override the newer overload, taking a wxWindow pointer.
 
+- wxImageList size is now expressed in physical pixels, i.e. its size must be
+  the same as the size of bitmaps added to it, in pixels. This is inconvenient
+  but should be viewed as a hint not to use wxImageList (but wxBitmapBundle)
+  in the applications supporting high DPI.
+
 
 Changes in behaviour which may result in build errors
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