Make 'stratis filesystem' list filesystems instead of printing help
Make 'stratis filesystem' list filesystems instead of printing help

Just like we previously did for pools and blockdevs.

Signed-off-by: Andy Grover <b7d524d2f5cc5aebadb6b92b08d3ab26911cde33@redhat.com>

stratis-storage/stratis-cli,stratis-storage/stratis-cli