[Media Files] Add an extensibility point to FetchMediaFilesFromContent component

Created by: roma-glushko

Current Behaviour Currently, deployment of media files works only for media that is added by {{media}} directive.

Desired Behaviour The {{media}} directive is not enough usually to cover all CMS content management needs. On the practice, media files can be used in CMS content from widgets as well.

It can be helpful to have an extensible point in FetchMediaFilesFromContent component to be able to compose custom media file queries to be able to fetch files from different places (like custom widget parameters)