Add option to share bookmarks publicly (#503)

* Make shared view public, add user profile fallback

* Allow unauthenticated access to shared bookmarks API

* Link shared bookmarks in unauthenticated layout

* Add public sharing setting

* Only show shared bookmarks link if there are publicly shared bookmarks

* Disable public sharing if sharing is disabled

* Show specific helper text when public sharing is enabled

* Fix tests

* Add more tests

* Improve setting description

bookmarks/migrations/0024_userprofile_enable_public_sharing.py

@@ -0,0 +1,18 @@
+# Generated by Django 4.1.9 on 2023-08-14 07:08
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('bookmarks', '0023_userprofile_permanent_notes'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='userprofile',
+            name='enable_public_sharing',
+            field=models.BooleanField(default=False),
+        ),
+    ]