Refactor application structure and add unit tests

Added:
- New `ProgressService` class for managing progress indicators.
- New `AssetDatabase`, `AssetOpenHandlerAttribute`, and `AsyncAssetOpenHandlerAttribute` classes for asset handling.
- `Ghost.UnitTest` project for unit testing with associated files and configurations.

Changed:
- `ActivationHandler` class to ensure correct handling of `LaunchActivatedEventArgs`.
- `App.xaml.cs` to register `INotificationService` and `IProgressService`, replacing `StackedNotificationService`.
- `OnLaunched` method in `App.xaml.cs` to correctly call `ActivationHandler.Handle(args)` and start the host.
- `INavigationAware` interface from internal to public for broader access.
- `EditorState.cs` to activate `EditorApplication` with the current service provider.
- Property names in `AssetItem` and `ExplorerItem` structs to `Name` and `FullName`.
- `NotificationService` class to implement `INotificationService` and refactor notification handling.
- `AssetPathToGlyphConverter` to handle file extensions consistently.
- Bindings in `ProjectPage.xaml` and `ProjectPage.xaml.cs` to use `FullName` instead of `Path`.
- `EngineEditorWindow` and `LandingWindow` classes to utilize new notification and progress services.
- `Logger` class to include a new method for logging errors with exceptions.

Updated:
- Manifest files and project files to reflect new structure and dependencies.
- Solution file `GhostEngine.sln` to include the new unit test project.
- Added several new test classes and methods in `UnitTests.cs`.

Ghost.UnitTest/Ghost.UnitTest.csproj

@@ -0,0 +1,80 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <OutputType>WinExe</OutputType>
+    <TargetFramework>net9.0-windows10.0.22621.0</TargetFramework>
+    <TargetPlatformMinVersion>10.0.17763.0</TargetPlatformMinVersion>
+    <RootNamespace>Ghost.UnitTest</RootNamespace>
+    <ApplicationManifest>app.manifest</ApplicationManifest>
+    <Platforms>x86;x64;ARM64</Platforms>
+    <RuntimeIdentifiers>win-x86;win-x64;win-arm64</RuntimeIdentifiers>
+    <PublishProfile>win-$(Platform).pubxml</PublishProfile>
+    <UseWinUI>true</UseWinUI>
+    <EnableMsixTooling>true</EnableMsixTooling>
+    <Nullable>enable</Nullable>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <Page Remove="UnitTestApp.xaml" />
+    <ApplicationDefinition Include="UnitTestApp.xaml" />
+    <ProjectCapability Include="TestContainer" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <Content Include="Assets\SplashScreen.scale-200.png" />
+    <Content Include="Assets\LockScreenLogo.scale-200.png" />
+    <Content Include="Assets\Square150x150Logo.scale-200.png" />
+    <Content Include="Assets\Square44x44Logo.scale-200.png" />
+    <Content Include="Assets\Square44x44Logo.targetsize-24_altform-unplated.png" />
+    <Content Include="Assets\StoreLogo.png" />
+    <Content Include="Assets\Wide310x150Logo.scale-200.png" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <Manifest Include="$(ApplicationManifest)" />
+  </ItemGroup>
+
+  <!-- 
+    Defining the "Msix" ProjectCapability here allows the Single-project MSIX Packaging
+    Tools extension to be activated for this project even if the Windows App SDK Nuget
+    package has not yet been restored.
+  -->
+  <ItemGroup Condition="'$(DisableMsixProjectCapabilityAddedByProject)'!='true' and '$(EnableMsixTooling)'=='true'">
+    <ProjectCapability Include="Msix" />
+  </ItemGroup>
+  <ItemGroup>
+    <PackageReference Include="Microsoft.TestPlatform.TestHost" Version="17.14.1" />
+    <PackageReference Include="Microsoft.Windows.SDK.BuildTools" Version="10.0.26100.4188" />
+    <PackageReference Include="Microsoft.WindowsAppSDK" Version="1.7.250513003" />
+    <PackageReference Include="MSTest.TestAdapter" Version="3.9.1" />
+    <PackageReference Include="MSTest.TestFramework" Version="3.9.1" />
+  </ItemGroup>
+  <ItemGroup>
+    <ProjectReference Include="..\Ghost.Editor\Ghost.Editor.csproj" />
+    <ProjectReference Include="..\Ghost.Engine\Ghost.Engine.csproj" />
+    <ProjectReference Include="..\Ghost.Entities\Ghost.Entities.csproj" />
+  </ItemGroup>
+  
+  <ItemGroup>
+    <Reference Include="Misaki.HighPerformance.Unsafe">
+      <HintPath>..\..\Class\Misaki.HighPerformance\Misaki.HighPerformance.Unsafe\bin\Release\net9.0\Misaki.HighPerformance.Unsafe.dll</HintPath>
+    </Reference>
+  </ItemGroup>
+
+  <!-- 
+    Defining the "HasPackageAndPublishMenuAddedByProject" property here allows the Solution 
+    Explorer "Package and Publish" context menu entry to be enabled for this project even if 
+    the Windows App SDK Nuget package has not yet been restored.
+  -->
+  <PropertyGroup Condition="'$(DisableHasPackageAndPublishMenuAddedByProject)'!='true' and '$(EnableMsixTooling)'=='true'">
+    <HasPackageAndPublishMenu>true</HasPackageAndPublishMenu>
+  </PropertyGroup>
+
+  <!-- Publish Properties -->
+  <PropertyGroup>
+    <PublishReadyToRun Condition="'$(Configuration)' == 'Debug'">False</PublishReadyToRun>
+    <PublishReadyToRun Condition="'$(Configuration)' != 'Debug'">True</PublishReadyToRun>
+    <PublishTrimmed>False</PublishTrimmed>
+    <SupportedOSPlatformVersion>10.0.20348.0</SupportedOSPlatformVersion>
+    <ImplicitUsings>enable</ImplicitUsings>
+  </PropertyGroup>
+</Project>