Add `rufo` rake tasks
Add `rufo` rake tasks

    $ rake -T rufo
    rake rufo                       # Alias for `rake rufo:run`
    rake rufo:check[files_or_dirs]  # Check that no formatting changes are produced
    rake rufo:run[files_or_dirs]    # Format Ruby code in current directory

ruby-formatter/rufo,ruby-formatter/rufo,ruby-formatter/rufo