BRUSSELS — An identity tool that underpins the digital lives of Dutch people and has partly fallen into American hands is prompting the country to reconsider its reliance on U.S. technology. In the Netherlands, almost every citizen regularly uses the online identification tool DigiD to book a doctor’s appointment, buy a house or access online public services. With a Dutch supplier of the tool in the process of being acquired by a U.S. technology company, that’s prompting concerns that the