forms: allow clicking back to any previous page (#11249)

@@ -1589,0 +1591,4 @@
+            previous_page_id = get_request().form.get('previous-page-id')
+            if previous_page_id:
+                new_page_no, previous_page = [
+                    x for x in enumerate(self.pages[:page_no]) if x[1].id == previous_page_id

@@ -1080,0 +1080,4 @@
+
+document.addEventListener('DOMContentLoaded', function(){
+  const previous_page_id_input = document.querySelector('[name="previous-page-id"]')
+  if (!previous_page_id_input) return

@@ -1080,0 +1086,4 @@
+      if (e.key !== "Enter" && e.key !== " ") return
+      e.preventDefault()
+      previous_page_id_input.value = step.dataset.pageId
+      document.querySelector('button[name="previous"]').dispatchEvent(new MouseEvent('click'))

@@ -1080,0 +1090,4 @@
+    })
+    step.addEventListener('click', function() {
+      previous_page_id_input.value = step.dataset.pageId
+      document.querySelector('button[name="previous"]').dispatchEvent(new MouseEvent('click'))

@@ -21,0 +21,4 @@
+              {% if forloop.counter < current_page_no %}
+                aria-label="{% blocktrans with page_label=page_label %}Go back to step: {{ page_label }}{% endblocktrans %}"
+                role="button"
+                tabindex="0"