ProjectManager: Add convenience Task subclasses

For Compile, BuildSystem and Deployment. Unclutters user code and reduces
binary size.

Change-Id: Ia18e917bb411754162e9f4ec6056d752a020bb50
Reviewed-by: Christian Kandeler <christian.kandeler@qt.io>

src/plugins/qmakeprojectmanager/qmakebuildconfiguration.cpp

@@ -769,9 +769,8 @@ QmakeBuildConfigurationFactory::QmakeBuildConfigurationFactory()
         if (QmakeSettings::warnAgainstUnalignedBuildDir()
                 && !QmakeBuildConfiguration::isBuildDirAtSafeLocation(
                     QFileInfo(projectPath).absoluteDir().path(), QDir(buildDir).absolutePath())) {
-            issues.append(Task(Task::Warning, QmakeBuildConfiguration::unalignedBuildDirWarning(),
-                               Utils::FilePath(), -1,
-                               ProjectExplorer::Constants::TASK_CATEGORY_BUILDSYSTEM));
+            issues.append(BuildSystemTask(Task::Warning,
+                                          QmakeBuildConfiguration::unalignedBuildDirWarning()));
         }
         return issues;
     });