[ENTITY][AttachmentThumbnail] Now thumbnails are always only available in three sizes: small, medium, big

Commit jointly produced with eli (Eliseu Amaro)

Breaking change: Entity changed to only store the tinyint referring to the size stored

With this, the logic was simplified and now it's not possible to make an
instance produce unnecessary thumbs. The aspect ratio is preserved and
thus the thumbs will always look nice. New configuration was added to
maintain flexibility.

plugins/StoreRemoteMedia/StoreRemoteMedia.php

@@ -157,7 +157,7 @@ class StoreRemoteMedia extends Plugin
             // Create an attachment for this
             $temp_file = new TemporaryFile();
             $temp_file->write($media);
-            $attachment = GSFile::sanitizeAndStoreFileAsAttachment($temp_file);
+            $attachment = GSFile::storeFileAsAttachment($temp_file);
 
             // Relate the link with the attachment
             DB::persist(AttachmentToLink::create([
@@ -177,8 +177,7 @@ class StoreRemoteMedia extends Plugin
             if (!$this->getStoreOriginal()) {
                 $thumbnail = AttachmentThumbnail::getOrCreate(
                     attachment: $attachment,
-                    width: $this->getThumbnailWidth(),
-                    height: $this->getThumbnailHeight(),
+                    size: 'small',
                     crop: $this->getSmartCrop()
                 );
                 $attachment->deleteStorage();