[New Command] List of suggests

For composer project this command has output:
```sh
$ bin/composer suggests -D
Suggests:
  Nothing!
Dev suggests:
  phpunit/php-code-coverage:
    "ext-dom": "*"
    "ext-xdebug": ">=2.0.5"
  phpunit/phpunit:
    "ext-json": "*"
    "ext-simplexml": "*"
    "ext-tokenizer": "*"
    "phpunit/php-invoker": ">=1.1.0,<1.2.0"
  phpunit/phpunit-mock-objects:
    "ext-soap": "*"
```