FIX: pass sidebar custom link willDestroy (#17565)

Custom sidebar link willDestroy function has to be passed to SidebarLink component to call when component is removed.

Very similar to https://github.com/discourse/discourse/pull/17551

app/assets/javascripts/discourse/app/components/sidebar/section-link.js

@@ -2,6 +2,12 @@ import GlimmerComponent from "@glimmer/component";
 import { htmlSafe } from "@ember/template";
 
 export default class SectionLink extends GlimmerComponent {
+  willDestroy() {
+    if (this.args.willDestroy) {
+      this.args.willDestroy();
+    }
+  }
+
   get prefixCSS() {
     const color = this.args.prefixColor;
     if (!color || !color.match(/^\w{6}$/)) {

app/assets/javascripts/discourse/app/templates/components/sidebar/sections.hbs

@@ -39,6 +39,7 @@
           @hoverAction={{link.hoverAction}}
           @hoverTitle={{link.hoverTitle}}
           @currentWhen={{link.currentWhen}}
+          @willDestroy={{link.willDestroy}}
           @content={{link.text}} />
       {{/each}}
     </Sidebar::Section>

app/assets/javascripts/discourse/tests/acceptance/sidebar-plugin-api-test.js

@@ -9,13 +9,17 @@ import {
 } from "discourse/tests/helpers/qunit-helpers";
 import { withPluginApi } from "discourse/lib/plugin-api";
 import { resetSidebarSection } from "discourse/lib/sidebar/custom-sections";
+import { bind } from "discourse-common/utils/decorators";
 
 acceptance("Sidebar - section API", function (needs) {
   needs.user({ experimental_sidebar_enabled: true });
 
   needs.hooks.afterEach(() => {
     resetSidebarSection();
+    linkDestroy = undefined;
+    sectionDestroy = undefined;
   });
+  let linkDestroy, sectionDestroy;
 
   test("Multiple header actions and links", async function (assert) {
     withPluginApi("1.3.0", (api) => {
@@ -54,6 +58,10 @@ acceptance("Sidebar - section API", function (needs) {
                 },
               ];
             }
+            @bind
+            willDestroy() {
+              sectionDestroy = "section test";
+            }
             get links() {
               return [
                 new (class extends BaseCustomSidebarSectionLink {
@@ -93,6 +101,10 @@ acceptance("Sidebar - section API", function (needs) {
                   get suffixCSSClass() {
                     return "unread";
                   }
+                  @bind
+                  willDestroy() {
+                    linkDestroy = "link test";
+                  }
                 })(),
                 new (class extends BaseCustomSidebarSectionLink {
                   get name() {
@@ -275,6 +287,17 @@ acceptance("Sidebar - section API", function (needs) {
       "hover button title attribute",
       "displays hover button with correct title"
     );
+    await click(".header-sidebar-toggle button");
+    assert.strictEqual(
+      linkDestroy,
+      "link test",
+      "calls link willDestroy function"
+    );
+    assert.strictEqual(
+      sectionDestroy,
+      "section test",
+      "calls section willDestroy function"
+    );
   });
 
   test("Single header action and no links", async function (assert) {