FEATURE: Add export poll button (#8370)

This PR aims to make poll results easily exportable to staff in a CSV format, so they can be analyzed in external software.

It also makes the export data easily customizable by allowing users to leverage any data explorer query to generate the report. By default, we use a query that ships with data explorer, but user can change the ID in settings or use 0 to disable this feature.

One potential upgrade is using the recent work that allows arbitrary group to run data explorer and allow all the groups with access to the configured query to also export polls, but that can be added later.

Co-Authored-By: Joffrey JAFFEUX <j.jaffeux@gmail.com>

plugins/poll/assets/stylesheets/desktop/poll.scss

@@ -36,6 +36,10 @@ div.poll {
       line-height: 2em;
     }
 
+    :not(:first-child):not(:last-child) {
+      margin-left: 1em;
+    }
+
     .toggle-status {
       float: right;
     }