MDL-67122 forumreport_summary: Fix template context eg and line length

The template context needed updating now it populates a single select
and the summary_table constructor params should be broken over 2 lines

mod/forum/report/summary/classes/summary_table.php

@@ -103,7 +103,8 @@ class summary_table extends table_sql {
      * @param bool $canseeprivatereplies Whether the user can see all private replies or not.
      * @param int $perpage The number of rows to display per page.
      */
-    public function __construct(int $courseid, array $filters, bool $allowbulkoperations, bool $canseeprivatereplies, int $perpage) {
+    public function __construct(int $courseid, array $filters, bool $allowbulkoperations,
+            bool $canseeprivatereplies, int $perpage) {
         global $USER, $OUTPUT;
 
         $forumid = $filters['forums'][0];

mod/forum/report/summary/templates/bulk_action_menu.mustache

@@ -47,7 +47,20 @@
                 "value": "#messageselect"
             }
         ],
-        "perpage" : "<div class='singleselect'></div>"
+        "perpage": {
+            "name": "perpage",
+            "method": "get",
+            "action": "#",
+            "classes": "singleselect",
+            "label": "Per page",
+            "formid": "randomid",
+            "id": "selectperpage",
+            "options":[
+                {"value": 50, "name": "50", "selected": true},
+                {"value": 100, "name": "100", "selected":false},
+                {"value": 200, "name": "200", "selected": false}
+            ]
+        }
     }
 }}