Make OpenPower specific dump an optional feature

Make all OpenPower dumps as optional feature and should be
enabled in the configuration. System dump is the currently
implemented example of OpenPower dump. BMC dump will be
enabled by default.

To enable
openpower-dumps-extension=enabled

Test:
Tested all existing dump operations using automated
testing.

Signed-off-by: Dhruvaraj Subhashchandran <dhruvaraj@in.ibm.com>
Change-Id: If20b4711dfcf02a2a8ea23848f7409576813c832
diff --git a/dump-extensions.hpp b/dump-extensions.hpp
new file mode 100644
index 0000000..ad5b688
--- /dev/null
+++ b/dump-extensions.hpp
@@ -0,0 +1,21 @@
+#include "dump_manager.hpp"
+
+#include <memory>
+#include <vector>
+
+namespace phosphor
+{
+namespace dump
+{
+
+using DumpManagerList = std::vector<std::unique_ptr<phosphor::dump::Manager>>;
+/**
+ * @brief load the dump extensions
+ *
+ * @param[in] bus - Bus to attach to
+ * @param[out] dumpMgrList - list dump manager objects.
+ *
+ */
+void loadExtensions(sdbusplus::bus::bus& bus, DumpManagerList& dumpMgrList);
+} // namespace dump
+} // namespace phosphor