ProjectExplorer: Move some build-related code to BuildManager

The projectexplorer.cpp file is a huge mixed bag, which could use some
cleaning up. The queue() function is very much related to the
BuildManager, so move it there.

Change-Id: Ibc6425cc27d44514803a5e7c6139f83ddd760382
Reviewed-by: hjk <hjk@qt.io>

src/plugins/autotest/testrunner.cpp

@@ -651,7 +651,7 @@ void TestRunner::buildProject(Project *project)
                              buildManager, &BuildManager::cancel);
     connect(buildManager, &BuildManager::buildQueueFinished,
             this, &TestRunner::buildFinished);
-    ProjectExplorerPlugin::buildProject(project);
+    buildManager->buildProjectWithDependencies(project);
     if (!buildManager->isBuilding())
         buildFinished(false);
 }