LAS VEGAS — President Barack Obama’s choice of a Las Vegas high school to launch his immigration reform effort Tuesday illustrated yet again the way Latinos are reshaping Nevada’s political landscape.The president flew to the Mojave Desert to hold a campaign-style event aimed at drawing support for his proposal to give millions of illegal immigrants a pathway to citizenship. He spoke at Del Sol High School, where Latinos account for 58 percent of the student body.During the first trip of his second term, Obama praised a plan unveiled by a bipartisan group of senators the day before, and led the …