Add NUM_VALUES for enums and size for structs (see #3836)

API versioning requires that enumerations end with a count value
(`*_NUM_VALUES`) and structs begin with a size value (`size_t size`).
Wrapper templates are updated to support structs with different size
values indicating different versions.

To test:
Run `ceftests --gtest_filter=ApiVersionTest.StructVersion*`

libcef/browser/file_dialog_manager.cc

@@ -300,6 +300,9 @@ void CefFileDialogManager::RunFileDialog(
     case FILE_DIALOG_SAVE:
       params.mode = blink::mojom::FileChooserParams::Mode::kSave;
       break;
+    case FILE_DIALOG_NUM_VALUES:
+      DCHECK(false);
+      return;
   }
 
   params.title = title;