build(wrapping): Fix missing wrapped type for itkWasmTransformIO

Only templated variants for double and float are available,
so alias to the double version of transforms for wrapping.

ITK/build-python/Wrapping/castxml_inputs/itkWasmTransformIO.cxx:26:39:
error: no type named 'WasmTransformIO' in namespace 'itk'
   26 |         using itkWasmTransformIO=itk::WasmTransformIO;
      |                                  ~~~~~^

Author: hjmjohnson

include/itkWasmTransformIO.h

@@ -147,6 +147,7 @@ ITK_GCC_PRAGMA_DIAG(ignored "-Wattributes")
 
 extern template class WebAssemblyInterface_EXPORT_EXPLICIT WasmTransformIOTemplate<double>;
 extern template class WebAssemblyInterface_EXPORT_EXPLICIT WasmTransformIOTemplate<float>;
+using WasmTransformIO = WasmTransformIOTemplate<double>;
 
 ITK_GCC_PRAGMA_DIAG_POP()