LOS ANGELES, Oct 6 (Reuters) - When Bari Weiss walks into CBS News as editor-in-chief, she'll bring something the former home of Edward R. Murrow and Walter Cronkite has not seen in its nearly century-long history: a leader whose career has been built on challenging journalism’s most august institutions. The 41-year-old journalist's ascent from opinion page and book review editor to network news chief represents one of the most unorthodox appointments in broadcast journalism history. Sign up here. BUILT A MEDIA COMPANY FROM SCRATCH Unlike her predecessors, Weiss has never managed a television newsroom, never operated foreign bureaus, and is...