ui: Add a button to refresh grades

ui/src/routes/works/[wid]/+page.svelte

@@ -60,7 +60,15 @@
     {/if}
 
     <hr>
-    <h3 class="mt-3">Notes</h3>
+    <div class="d-flex justify-content-between align-items-center">
+        <h3 class="mt-3">Notes</h3>
+        <button
+            class="btn btn-light"
+            on:click={() => refresh_grades(w)}
+        >
+            <i class="bi bi-arrow-clockwise"></i>
+        </button>
+    </div>
     <div class="card mt-3 mb-5">
         {#await gradesP}
             <div class="text-center mb-5">