Fix failing test

This test used to pass with VSTest and xunit v2 because the tests were run under testhost.exe.

So, DistributedApplicationOptions.Assembly was pointing to testhost. Then ResolveProjectDirectory wouldn't correctly find AppHostProjectPath. In DistributedApplicationBuilder constructor, we were falling back to _innerBuilder.Environment.ContentRootPath because ProjectDirectory is null.

With xunit.v3 *or* MTP, generally when the test app is executed as normal executable, we have the right assembly and we are able to resolve project directory correctly

Author: Youssef1313

tests/Aspire.Hosting.Tests/ExecutableResourceTests.cs

@@ -49,12 +49,13 @@ public async Task AddExecutableWithArgs()
             );
 
         var manifest = await ManifestUtils.GetManifest(exe2.Resource).DefaultTimeout();
-
+        // Note: resource working directory is <repo-root>\tests\Aspire.Hosting.Tests
+        // Manifest directory is <repo-root>\artifacts\bin\Aspire.Hosting.Tests\Debug\net8.0
         var expectedManifest =
         """
         {
           "type": "executable.v0",
-          "workingDirectory": ".",
+          "workingDirectory": "../../../../../tests/Aspire.Hosting.Tests",
           "command": "python",
           "args": [
             "app.py",