Fixed canari list-transforms

Fixes:
 * Now has the correct help messages, and not the copy/paste from the
   install-package command.
 * Now has a -d/--src-dir argument instead of the copy/paste
   --working-dir from the install-package command.
 * Will now try and guess the --src-dir argument if not specified, just
   as the create-transform command will try and guess the transform
   directory by using information from project_tree().
 * Will now infer the package name if it is not specified, and if a
   valid --src-dir or current working directory is used. Valid being a
   transform package directory such that project_tree() will return
   useful information.
Change to ValueError. When caught, the working directory should be '.'. This way, the list-transforms command can work on site-package installed transform packs.