allow chaining of ->newLine() (#41327)

```php
$this->newLine();
$this->info('Success!');
```

can now be shortened to

```php
$this->newLine()->info('Success');
```

src/Illuminate/Console/Concerns/InteractsWithIO.php

@@ -372,11 +372,13 @@ public function alert($string)
      * Write a blank line.
      *
      * @param  int  $count
-     * @return void
+     * @return $this
      */
     public function newLine($count = 1)
     {
         $this->output->newLine($count);
+
+        return $this;
     }
 
     /**