Brian Steinberg Senior TV EditorA new lineup of Saturday programming and a surge of post-pandemic spending by Madison Avenue helped the CW boost its volume of advertising commitments in TV’s annual “upfront” market, a sign that advertisers continue to make the medium a central part of their plans even as they are showing new interest in chasing viewers to new streaming venues.The network, jointly owned by ViacomCBS and AT&T’s WarnerMedia, has wrapped its upfront negotiations, according to a