Updates the GUI to start the launcher

instead of the real agent, which is now a CLI application

Also updates test code that builds the agent

The GUI expects the launcher now.

gui/packages/ubuntupro/integration_test/utils/build_agent.dart

@@ -7,7 +7,7 @@ import 'package:path/path.dart' as p;
 /// A try-catch block (on AssertionError) can still prevent process exit.
 Future<void> buildAgentExe(
   String destination, {
-  String exeName = 'ubuntu-pro-agent.exe',
+  String exeName = 'ubuntu-pro-agent-launcher.exe',
 }) async {
   const config = 'Debug';
   const platform = 'x64';

gui/packages/ubuntupro/lib/constants.dart

@@ -11,4 +11,4 @@ const kAddrFileName = 'addr';
 const kDefaultMargin = 32.0;
 
 /// The path of the agent executable relative to the msix root directory.
-const kAgentRelativePath = 'agent/ubuntu-pro-agent.exe';
+const kAgentRelativePath = 'agent/ubuntu-pro-agent-launcher.exe';