Added ES6 local support for formatNumber helper as per #2951 (#3099)

framework/core/js/src/common/utils/formatNumber.ts

@@ -1,11 +1,13 @@
+import app from '../../forum/app';
+
 /**
  * The `formatNumber` utility localizes a number into a string with the
- * appropriate punctuation.
+ * appropriate punctuation based on the provided locale otherwise will default to the users locale.
  *
  * @example
  * formatNumber(1234);
  * // 1,234
  */
-export default function formatNumber(number: number): string {
+export default function formatNumber(number: number, locale: string = app.data.locale): string {
-  return number.toString().replace(/\B(?=(\d{3})+(?!\d))/g, ',');
+  return new Intl.NumberFormat(locale).format(number);
 }