ChatPanel: Rename `chat` to `shoutbox`.

To remove confusion with the new ChatMessages.
3 jobs for chat-to-shoutbox in 7 minutes and 11 seconds (queued for 1 second)
Status Job ID Name Coverage
  Lint
passed #138479
lint

00:00:42

 
  Build
passed #138480
build

00:03:06

 
  Test
passed #138481
test

00:03:22