Fix size of some bitmaps returned by wxWindowsArtProvider.

Bitmaps obtained using SHGetStockIconInfo can have only some predefined sizes.
If size of the retrieved bitmap doesn't correspond to the needed size or the
size given by wxArtProvider::GetNativeSizeHint() then the bitmap should be
rescaled appropriately.

Closes #17071.

Closes https://github.com/wxWidgets/wxWidgets/pull/64

src/msw/artmsw.cpp

@@ -197,7 +197,20 @@ wxBitmap wxWindowsArtProvider::CreateBitmap(const wxArtID& id,
             ::DestroyIcon(sii.hIcon);
 
             if ( bitmap.IsOk() )
+            {
+                const wxSize
+                    sizeNeeded = size.IsFullySpecified()
+                                    ? size
+                                    : wxArtProvider::GetNativeSizeHint(client);
+
+                if ( sizeNeeded.IsFullySpecified() &&
+                        bitmap.GetSize() != sizeNeeded )
+                {
+                    wxArtProvider::RescaleBitmap(bitmap, sizeNeeded);
+                }
+
                 return bitmap;
+            }
         }
     }
 #endif // wxHAS_SHGetStockIconInfo