refactor: replace debounce/throttle deps with first-party code (#38610)

Adds `web_src/js/utils/func.ts` with `debounce` and `throttle`, dropping
`throttle-debounce` and `perfect-debounce` dependencies. Both were
needed before: the former has no promise-returning debounce, which
`TextExpander` requires, and the latter no `throttle`.

Signature follows lodash and es-toolkit: `(func, wait, {leading,
trailing})` plus `cancel`, so argument order flips at the migrated call
sites.

web_src/js/webcomponents/overflow-menu.ts

@@ -1,4 +1,4 @@
-import {throttle} from 'throttle-debounce';
+import {throttle} from '../utils/func.ts';
 import {addDelegatedEventListener, generateElemId, isDocumentFragmentOrElementNode} from '../utils/dom.ts';
 import octiconKebabHorizontal from '../../../public/assets/img/svg/octicon-kebab-horizontal.svg';
 
@@ -37,7 +37,7 @@ window.customElements.define('overflow-menu', class extends HTMLElement {
     }
   };
 
-  updateItems = throttle(100, () => {
+  updateItems = throttle(() => {
     if (!this.popup) {
       const div = document.createElement('div');
       div.classList.add('overflow-menu-popup');
@@ -183,7 +183,7 @@ window.customElements.define('overflow-menu', class extends HTMLElement {
     this.append(this.button);
     this.append(this.popup);
     this.updateButtonActivationState();
-  });
+  }, 100);
 
   init() {
     // for horizontal menus where fomantic boldens active items, prevent this bold text from