The Republican National Committee on Friday selected new leaders who were handpicked by former President Donald J. Trump‚ a move expected to tighten the expected nominee’s hold on the party’s machinery ahead of the general election. The committee unanimously elected Michael Whatley‚ who led the North Carolina Republican Party and was the R.N.C.’s general counsel‚ as its chair and Lara Trump‚ Mr. Trump’s daughter-in-law‚ as co-chair. Both Mr. Whatley and Ms. Trump were endorsed by Mr....