JS: mark the addCustomOutput method as private
JS: mark the addCustomOutput method as private

This should only be called from the updateForInput callback to actually
add the handles.

Signed-off-by: Harvey Harrison <eadbd6b462bf3c97df0300a934c12bc2e5d1fe51@gmail.com>

jaamsim/jaamsim,jaamsim/jaamsim,jaamsim/jaamsim,jaamsim/jaamsim