Former President Donald J. Trump and the Republican Party out-raised President Biden and the Democrats last month for the first time in this election cycle, according to campaign officials, as Mr. Biden’s pace of fund-raising slowed significantly from March. Mr. Trump’s advisers have said privately that his campaign, together with the Republican Party and all of their affiliated committees, raised $76.2 million in April. The Biden campaign said on Monday evening that it had raised $51...