[CmdPal][UnitTests] Add/Migrate unit test for Apps and Bookmarks extension (#41238)

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fix/what does it change/how was it tested (even manually, if necessary)?
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## Summary of the Pull Request
1. Create Apps and Bookmarks ut project.
2. Refactor Apps and Bookmarks. And some interface in these extensions
to add a abstraction layer for testing purpose.
New interface list:
* ISettingsInterface
* IUWPApplication
* IAppCache
* IBookmarkDataSource
3. Add/Migrate some test case for Apps and Bookmarks extension

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## PR Checklist

- [x] Closes: #41239 #41240
- [x] **Communication:** I've discussed this with core contributors
already. If the work hasn't been agreed, this work might be rejected
- [x] **Tests:** Added/updated and all pass
- [ ] **Localization:** All end-user-facing strings can be localized
- [ ] **Dev docs:** Added/updated
- [ ] **New binaries:** Added on the required places
- [ ] [JSON for
signing](https://github.com/microsoft/PowerToys/blob/main/.pipelines/ESRPSigning_core.json)
for new binaries
- [ ] [WXS for
installer](https://github.com/microsoft/PowerToys/blob/main/installer/PowerToysSetup/Product.wxs)
for new binaries and localization folder
- [ ] [YML for CI
pipeline](https://github.com/microsoft/PowerToys/blob/main/.pipelines/ci/templates/build-powertoys-steps.yml)
for new test projects
- [ ] [YML for signed
pipeline](https://github.com/microsoft/PowerToys/blob/main/.pipelines/release.yml)
- [ ] **Documentation updated:** If checked, please file a pull request
on [our docs
repo](https://github.com/MicrosoftDocs/windows-uwp/tree/docs/hub/powertoys)
and link it here: #xxx

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or any additional comments/features here -->
## Detailed Description of the Pull Request / Additional comments

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---------

Co-authored-by: Yu Leng <yuleng@microsoft.com>
Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

src/modules/cmdpal/Tests/Microsoft.CmdPal.Ext.Apps.UnitTests/QueryTests.cs

@@ -0,0 +1,45 @@
+// Copyright (c) Microsoft Corporation
+// The Microsoft Corporation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System.Linq;
+using Microsoft.CmdPal.Ext.UnitTestBase;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+
+namespace Microsoft.CmdPal.Ext.Apps.UnitTests;
+
+[TestClass]
+public class QueryTests : CommandPaletteUnitTestBase
+{
+    [TestMethod]
+    public void QueryReturnsExpectedResults()
+    {
+        // Arrange
+        var mockCache = new MockAppCache();
+        var win32App = TestDataHelper.CreateTestWin32Program("Notepad", "C:\\Windows\\System32\\notepad.exe");
+        var uwpApp = TestDataHelper.CreateTestUWPApplication("Calculator");
+        mockCache.AddWin32Program(win32App);
+        mockCache.AddUWPApplication(uwpApp);
+
+        for (var i = 0; i < 10; i++)
+        {
+            mockCache.AddWin32Program(TestDataHelper.CreateTestWin32Program($"App{i}"));
+            mockCache.AddUWPApplication(TestDataHelper.CreateTestUWPApplication($"UWP App {i}"));
+        }
+
+        var page = new AllAppsPage(mockCache);
+        var provider = new AllAppsCommandProvider(page);
+
+        // Act
+        var allItems = page.GetItems();
+
+        // Assert
+        var notepadResult = Query("notepad", allItems).FirstOrDefault();
+        Assert.IsNotNull(notepadResult);
+        Assert.AreEqual("Notepad", notepadResult.Title);
+
+        var calculatorResult = Query("cal", allItems).FirstOrDefault();
+        Assert.IsNotNull(calculatorResult);
+        Assert.AreEqual("Calculator", calculatorResult.Title);
+    }
+}