CMakeProjectManager: Use CMAKE_HOME_DIRECTORY as source directory

The CMakeCache.txt file has CMAKE_HOME_DIRECTORY pointing to the
project source directory used to configure the project.

When importing a cmake build the CMAKE_HOME_DIRECTORY from
CMakeCache.txt might not point to the same CMakeLists.txt that was
opened as a project.

qt-cmake-standalone-test from Qt6 uses a CMake template project which
does a add_subdirectory with the test source directory, which will not
work if opened standalone.

Normally this is a user error though, so ask the user if this was
intended, before actually importing the build.

Task-number: QTBUG-88776
Change-Id: Ifdd5e1d1cb8a1ef9955d22493eba3a1a55dc689f
Reviewed-by: Leena Miettinen <riitta-leena.miettinen@qt.io>
Reviewed-by: Cristian Adam <cristian.adam@qt.io>

src/plugins/cmakeprojectmanager/cmakebuildconfiguration.h

@@ -67,6 +67,9 @@ public:
 
     void runCMakeWithExtraArguments();
 
+    void setSourceDirectory(const Utils::FilePath& path);
+    Utils::FilePath sourceDirectory() const;
+
 signals:
     void errorOccurred(const QString &message);
     void warningOccurred(const QString &message);
@@ -133,5 +136,13 @@ public:
     InitialCMakeArgumentsAspect();
 };
 
+class SourceDirectoryAspect final : public Utils::StringAspect
+{
+    Q_OBJECT
+
+public:
+    SourceDirectoryAspect();
+};
+
 } // namespace Internal
 } // namespace CMakeProjectManager