Improve "goto issue by number" button (#24577)

Follow #24479


![image](https://user-images.githubusercontent.com/2114189/236694114-c5cb42ff-456d-465a-bcb9-89ed5959d346.png)


![image](https://user-images.githubusercontent.com/2114189/236694119-052e689c-6264-4468-9ab3-0e5c97521bec.png)


![image](https://user-images.githubusercontent.com/2114189/236694139-f8940765-42ce-462d-b49e-50a416cc6f85.png)


![image](https://user-images.githubusercontent.com/2114189/236694154-6d8a000c-9ef3-4d07-af1c-59b0cf8f4d33.png)


![image](https://user-images.githubusercontent.com/2114189/236694166-3bc3e585-7955-44aa-af34-b33ae91e132f.png)

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

web_src/js/utils/dom.js

@@ -1,3 +1,5 @@
+import {debounce} from 'throttle-debounce';
+
 function elementsCall(el, func, ...args) {
   if (typeof el === 'string' || el instanceof String) {
     el = document.querySelectorAll(el);
@@ -42,6 +44,13 @@ export function toggleElem(el, force) {
   elementsCall(el, toggleShown, force);
 }
 
+export function isElemHidden(el) {
+  const res = [];
+  elementsCall(el, (e) => res.push(e.classList.contains('gt-hidden')));
+  if (res.length > 1) throw new Error(`isElemHidden doesn't work for multiple elements`);
+  return res[0];
+}
+
 export function onDomReady(cb) {
   if (document.readyState === 'loading') {
     document.addEventListener('DOMContentLoaded', cb);
@@ -170,3 +179,7 @@ export function autosize(textarea, {viewportMarginBottom = 0} = {}) {
     }
   };
 }
+
+export function onInputDebounce(fn) {
+  return debounce(300, fn);
+}