refactor(frontend): replace legacy utils JS files with typed TS equivalents

frontend/src/static/js/utils/helpers/csrfToken.ts

@@ -0,0 +1,18 @@
+export function csrfToken() {
+    let cookieVal = null;
+
+    if (document.cookie && '' !== document.cookie) {
+        const cookies = document.cookie.split(';');
+        let i = 0;
+        while (i < cookies.length) {
+            const cookie = cookies[i].trim();
+            if ('csrftoken=' === cookie.substring(0, 10)) {
+                cookieVal = decodeURIComponent(cookie.substring(10));
+                break;
+            }
+            i += 1;
+        }
+    }
+
+    return cookieVal;
+}