ProjectExplorer: Split ApplicationLauncher::start() parameters

There's traditionally an odd duplication of the runnable.device
and the passed device here. Start disentangling things.

Change-Id: I1cc1628c99cea04d761fc4d8dd0cb232127ce055
Reviewed-by: Jarek Kobus <jaroslaw.kobus@qt.io>
Reviewed-by: <github-actions-qt-creator@cristianadam.eu>

src/plugins/boot2qt/qdbdevicedebugsupport.cpp

@@ -118,7 +118,8 @@ public:
         r.command.setArguments(args);
         r.command.setExecutable(FilePath::fromString(Constants::AppcontrollerFilepath));
 
-        m_launcher.start(r, device());
+        m_launcher.setRunnable(r);
+        m_launcher.start(device());
     }
 
     void stop() override { m_launcher.stop(); }