libcalamares: add accessor for settings path

src/libcalamares/Settings.cpp

@@ -250,6 +250,7 @@ Settings::Settings( bool debugMode )
 
 Settings::Settings( const QString& settingsFilePath, bool debugMode )
     : QObject()
+    , m_settingsPath( settingsFilePath )
     , m_debug( debugMode )
     , m_doChroot( true )
     , m_promptInstall( false )

src/libcalamares/Settings.h

@@ -89,6 +89,9 @@ public:
     /// @brief Explicif filename, debug is always true (for testing)
     static Settings* init( const QString& filename );
 
+    /// @brief Get the path this settings was created for (may be empty)
+    QString path() const { return m_settingsPath; }
+
     QStringList modulesSearchPaths() const;
 
     using InstanceDescriptionList = QList< InstanceDescription >;
@@ -177,6 +180,7 @@ public:
 
 private:
     static Settings* s_instance;
+    QString m_settingsPath;
 
     QStringList m_modulesSearchPaths;