Prettify number of issues (#17760)

* Prettify number of issues

- Use the PrettyNumber function to add commas in large amount of issues.

* Use client-side formatting

* prettify on both server and client

* remove unused i18n entries

* handle more cases, support other int types in PrettyNumber

* specify locale to avoid issues with node default locale

* remove superfluos argument

* introduce template helper, octicon tweaks, js refactor

* Update modules/templates/helper.go

* Apply some suggestions.

* Add comment

* Update templates/user/dashboard/issues.tmpl

Co-authored-by: silverwind <me@silverwind.io>

Co-authored-by: silverwind <me@silverwind.io>
Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>

web_src/js/features/formatting.js

@@ -0,0 +1,14 @@
+import {prettyNumber} from '../utils.js';
+
+const {lang} = document.documentElement;
+
+export function initFormattingReplacements() {
+  // replace english formatted numbers with locale-specific separators
+  for (const el of document.getElementsByClassName('js-pretty-number')) {
+    const num = Number(el.getAttribute('data-value'));
+    const formatted = prettyNumber(num, lang);
+    if (formatted && formatted !== el.textContent) {
+      el.textContent = formatted;
+    }
+  }
+}