Create data fetching wrapper for Image Gallery component

When using an Image Gallery inside of an article, it should be possible to use three different ways to reference all the pictures that should be included in the gallery:

• Use a complete folder (e.g. <ImageGallery folder="/my-blog-post/images" />) – all images inside this folder should be included
• Use a complete folder but exclude certain files (e.g. <ImageGallery folder="/my-blog-post/images" exclude="image3.jpg" />)
• Use a list/array of separate files (e.g. <ImageGallery files={["/my-blog-post/images/image1.jpg", "/my-blog-post/images/image2.jpg"]}/>)