Bulk create HTML snapshots (#1132)

* Add option to create HTML snapshot for bulk edit

* Add the prerequisite for displaying the "Create HTML Snapshot" bulk action option

* Add test case

This test case covers the scenario where the bulk actions panel displays the corresponding options when the HTML snapshot feature is enabled.

* Use the existing `tasks.create_html_snapshots()` instead of the for loop

* Fix the exposure of `settings.LD_ENABLE_SNAPSHOTS` within `BookmarkListContext`

* add service tests

* cleanup context

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

bookmarks/templates/bookmarks/bulk_edit/bar.html

@@ -23,6 +23,9 @@
           <option value="bulk_unshare">Unshare</option>
         {% endif %}
         <option value="bulk_refresh">Refresh from website</option>
+        {% if bookmark_list.snapshot_feature_enabled %}
+          <option value="bulk_snapshot">Create HTML snapshot</option>
+        {% endif %}
       </select>
       <div class="tag-autocomplete d-none" ld-tag-autocomplete>
         <input name="bulk_tag_string" class="form-input input-sm" placeholder="Tag names..." variant="small">