Move single FAB API under the separate class

SingleFab class provides functionalities to support single FAB feature.
This commit moves the single FAB related API under SingleFab class.

Change-Id: I8d55cd2134f5812f83f5fc5033df097ab1b1f8f2
Signed-off-by: Anupama B R <anupama.b.r1@ibm.com>
diff --git a/vpd-manager/include/single_fab.hpp b/vpd-manager/include/single_fab.hpp
new file mode 100644
index 0000000..03c6cee
--- /dev/null
+++ b/vpd-manager/include/single_fab.hpp
@@ -0,0 +1,26 @@
+#pragma once
+
+#include <string>
+
+namespace vpd
+{
+/**
+ * @brief class to implement single fab feature.
+ *
+ * The class hosts functionalities required to support single FAB feature.
+ *
+ */
+class SingleFab
+{
+    // ToDo: public API to be implemented, which can be called by the user to
+    // support single FAB.
+
+  private:
+    /**
+     * @brief API to get IM value from persisted location.
+     *
+     * @return IM value on success, empty string otherwise.
+     */
+    std::string getImFromPersistedLocation() const noexcept;
+};
+} // namespace vpd