PEL: Collect information for a FRU callout

Add an API to the DataInterface class to collect the following fields
needed to add a FRU callout to a PEL:
* Location code
* FRU part number (The VINI/FN keyword)
* FRU CCIN (The VINI/CC keyword)
* FRU serial number (The VINI/SN keyword)

For now, this code requires that both of the 2 D-Bus interfaces that
contain these properties be present on the inventory path being passed
in.  In the future, some smarts may need to be added to the code for
cases when the path isn't a FRU itself, or maybe doesn't have its own
VPD.  It's also possible there will be community supplied code in the
future that could do this mapping, which is why this code isn't trying
to do it itself now.

In the cases where one or both of these interfaces don't exist, an
exception will be thrown by the underlying sdbusplus code, and the
caller of this will handle it appropriately.

Signed-off-by: Matt Spinler <spinler@us.ibm.com>
Change-Id: I8eb5752fa25fc0e2107df3c7145355bbb4f12cf4
diff --git a/test/openpower-pels/mocks.hpp b/test/openpower-pels/mocks.hpp
index 5781233..1654a9d 100644
--- a/test/openpower-pels/mocks.hpp
+++ b/test/openpower-pels/mocks.hpp
@@ -29,6 +29,10 @@
     MOCK_METHOD(std::string, getChassisState, (), (const override));
     MOCK_METHOD(std::string, getHostState, (), (const override));
     MOCK_METHOD(std::string, getMotherboardCCIN, (), (const override));
+    MOCK_METHOD(void, getHWCalloutFields,
+                (const std::string&, std::string&, std::string&, std::string&,
+                 std::string&),
+                (const override));
 
     void changeHostState(bool newState)
     {