add page numbers to comment and quote statuses

This adds the page number for quote and comment statuses where a page number is provided:

- all ActivityPub posts
- Explore cards for comments (quotes already have the page number)

This responds to #2136

bookwyrm/templates/snippets/status/content_status.html

@@ -112,6 +112,9 @@
                     {% with full=status.content|safe no_trim=status.content_warning itemprop="reviewBody" %}
                         {% include 'snippets/trimmed_text.html' %}
                     {% endwith %}
+                    {% if status.progress %}
+                    <div class="is-small is-italic has-text-right mr-3">{% trans "page" %} {{ status.progress }}</div>
+                    {% endif %}
                 {% endif %}
 
                 {% if status.attachments.exists %}