[libcalamares] Allow retrieving chroot mode from system (as well as settings)

src/libcalamares/utils/CalamaresUtilsSystem.cpp

@@ -243,4 +243,10 @@ System::getTotalDiskB() const
     return 0;
 }
 
+bool
+System::doChroot() const
+{
+    return m_doChroot;
+}
+
 }  // namespace

src/libcalamares/utils/CalamaresUtilsSystem.h

@@ -170,6 +170,8 @@ public:
      */
     DLLEXPORT quint64 getTotalDiskB() const;
 
+    DLLEXPORT bool doChroot() const;
+
 private:
     static System* s_instance;