Make Internet Archive integration opt-in (#250)

* Make web archive integration opt-in

* Add toast message about web archive integration opt-in

* Improve wording for web archive setting

* Add toast admin

* Fix toast clear button visited styles

* Add test for redirect

* Improve wording

* Ensure redirects to same domain

* Improve wording

* Fix snapshot test

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

bookmarks/context_processors.py

@@ -0,0 +1,12 @@
+from bookmarks.models import Toast
+
+
+def toasts(request):
+    user = request.user if hasattr(request, 'user') else None
+    toast_messages = Toast.objects.filter(owner=user, acknowledged=False) if user and user.is_authenticated else []
+    has_toasts = len(toast_messages) > 0
+
+    return {
+        'has_toasts': has_toasts,
+        'toast_messages': toast_messages,
+    }