add util.ts for sharing common functions between frontend and backend

src/util-frontend.js

@@ -5,19 +5,6 @@ import utc from "dayjs/plugin/utc";
 dayjs.extend(utc)
 dayjs.extend(timezone)
 
-export function sleep(ms) {
-    return new Promise(resolve => setTimeout(resolve, ms));
-}
-
-export function ucfirst(str) {
-    if (! str) {
-        return str;
-    }
-
-    const firstLetter = str.substr(0, 1);
-    return firstLetter.toUpperCase() + str.substr(1);
-}
-
 function getTimezoneOffset(timeZone) {
     const now = new Date();
     const tzString = now.toLocaleString("en-US", {