fix: prevent trashing of trashed assets (#10028)

* fix: prevent trashing of trashed assets

Motivation
----------
This will improve user experience by hiding a pointless action.

You can not trash a trashed asset again. It won't get any trashier than it already is.

How to test
-----------
1. Visit route `/trash`
2. Click on an asset
3. Press "Delete" on your keyboard
4. Nothing happens
5. Try to find the trash button in the top right
6. You can't find it

* refactor: follow @michelheusschen's review

See:
https://github.com/immich-app/immich/pull/10028#pullrequestreview-2105296755

* refactor:  follow @michelheusschen's 2nd review

See: https://github.com/immich-app/immich/pull/10028#discussion_r1632057833

web/src/lib/components/asset-viewer/asset-viewer-nav-bar.spec.ts

@@ -0,0 +1,41 @@
+import { resetSavedUser, user as userStore } from '$lib/stores/user.store';
+import { assetFactory } from '@test-data/factories/asset-factory';
+import { userAdminFactory } from '@test-data/factories/user-factory';
+import '@testing-library/jest-dom';
+import { render } from '@testing-library/svelte';
+import AssetViewerNavBar from './asset-viewer-nav-bar.svelte';
+
+describe('AssetViewerNavBar component', () => {
+  const additionalProps = {
+    showCopyButton: false,
+    showZoomButton: false,
+    showDetailButton: false,
+    showDownloadButton: false,
+    showMotionPlayButton: false,
+    showShareButton: false,
+    onZoomImage: () => {},
+    onCopyImage: () => {},
+  };
+
+  afterEach(() => {
+    vi.resetAllMocks();
+    resetSavedUser();
+  });
+
+  it('shows back button', () => {
+    const asset = assetFactory.build({ isTrashed: false });
+    const { getByTitle } = render(AssetViewerNavBar, { asset, ...additionalProps });
+    expect(getByTitle('go_back')).toBeInTheDocument();
+  });
+
+  describe('if the current user owns the asset', () => {
+    it('shows delete button', () => {
+      const ownerId = 'id-of-the-user';
+      const user = userAdminFactory.build({ id: ownerId });
+      const asset = assetFactory.build({ ownerId, isTrashed: false });
+      userStore.set(user);
+      const { getByTitle } = render(AssetViewerNavBar, { asset, ...additionalProps });
+      expect(getByTitle('delete')).toBeInTheDocument();
+    });
+  });
+});