Add asterisk after required blocks in StreamField

wagtail/wagtailadmin/static_src/wagtailadmin/scss/components/_streamfield.scss

@@ -42,6 +42,17 @@ li.sequence-member {
         }
     }
     
+    // Copied from page-editor.scss    
+    .struct-block li.required > label:after {
+        content: '*';
+        color: $color-red;
+        font-weight: bold;
+        display: inline-block;
+        margin-left: 0.5em;
+        line-height: 1em;
+        font-size: 13px;
+    }
+
     // The top level sequence doesn't have a sequnce-member-inner. This block is basically for things that should only affect inner blocks
     .sequence-member-inner {
         @include clearfix;

wagtail/wagtailadmin/templates/wagtailadmin/block_forms/struct.html

@@ -5,7 +5,7 @@
 
     <ul class="fields">
         {% for child in children.values %}
-            <li>
+            <li{% if child.block.field.required %} class="required"{% endif %}>
                 {% if child.block.label %}
                     <label{% if child.id_for_label %} for="{{ child.id_for_label }}"{% endif %}>{{ child.block.label }}</label>
                 {% endif %}