The Corporation for Public Broadcasting, which helps pay for PBS, NPR, 1,500 local radio and television stations as well as programs like “Sesame Street” and “Finding Your Roots,” said Friday that it would close after the U.S. government withdrew funding. The private, nonprofit corporation was founded in 1968 shortly after Congress authorized its formation. It now ends nearly six decades of fueling the production of renowned educational programming, cultural content and emergency alerts about natural disasters.