Fix Duplicate Attribute Render In Composer

Some attribute forms are displayed twice in composer
These attribtutes do not have a `composer.php`

If view was set to 'composer' the render method was called twice.

- Move 'composer' view checkout to
  Core\Attribute\Key\Key::render()`
- Check if `$view` is composer then check if `composer.php` file exists.
  If so set `$view` from 'composer' to 'form'