Use spatie/laravel-medialibrary for all medias

[wblondel]

Hello,

I noticed that spatie/laravel-medialibrary is only used for the shop Product model.

As a result, the storage/app/public folder is messy with a lot of images at the root.

In this PR:

• Three (3) media collections are explicitly defined: product-images, link-images, and post-images;
• Each media collection uses its own disk, defined in config/filesystems.php;
• The post-images and link-images media collections are single file collections
• The Filament resources were modified to get the images from the correct media collection
• A thumb media conversion is defined for all media collections
• The thumbnails are loaded on the Filament infolists / tables instead of the full images
• The full images are loaded on the views / edit pages
• The collections only accept image/jpeg files and this rule is enforced in Filament as well
• Product images are reorderable
• The blog_links.image and blog_posts.image fields are dropped