Add support for bookmark thumbnails (#721)

* Preview Image

* fix tests

* add test

* download preview image

* relative path

* gst

* details view

* fix tests

* Improve preview image styles

* Remove preview image URL from model

* Revert form changes

* update tests

* make it work in uwsgi

---------

Co-authored-by: Sascha Ißbrücker <sascha.issbruecker@gmail.com>

bookmarks/api/routes.py

@@ -99,7 +99,10 @@ class BookmarkViewSet(
         # Either return metadata from existing bookmark, or scrape from URL
         if bookmark:
             metadata = WebsiteMetadata(
-                url, bookmark.website_title, bookmark.website_description
+                url,
+                bookmark.website_title,
+                bookmark.website_description,
+                None,
             )
         else:
             metadata = website_loader.load_website_metadata(url)