[FEATURE] Register Content Types by DI tags

- Refactored content type manager to accept alias => service ID
  registrations.
- All content types must now use the `sulu.content.type` tag.

I choose to overwrite the existing ContentTypeManager and not provide any BC. We would have to update all the existing content types to use this new method.
Please add the Sulu file header

    /*
     * This file is part of the Sulu CMS.
     *
     * (c) MASSIVE ART WebServices GmbH
     *
     * This source file is subject to the MIT license that is bundled
     * with this source code in the file LICENSE.
     */