PARIS — Vice President Kamala Harris spent hours talking with Emmanuel Macron, the French president, managing to skirt a recent diplomatic rift between the two allies over an Australian submarine deal. She attended a conference on promoting democratic elections in Libya. And she secured a commitment for the United States to join a nonbinding international declaration to protect civilians against cyberattacks. During a tightly choreographed trip to France this week, Harris appeared determined to assert herself as a diplomatic asset for a president who believes he knows more about the process — and the vice presidency — than most. The...