Singer-songwriter Liz Phair announced a new tour the first week in March of 2020, about two weeks before the pandemic took over our daily lives. That tour didn’t happen, but the legendary musician is hosting a livestream this week, brought to you locally by Headliners Music Hall.  Phair’s gleaming indie-pop scattered with elements of punk, behind scathing social criticism and sharp honesty, has cast her as a unique voice of her generation. She even has a recently-released song called “Hey Lou,” remembering the mercurial Velvet Underground leader who tended to walk on the wild side.