Refactor chassisInterfaces into chassis_utils

Some (e.g. IBM) do not use the
`xyz.openbmc_project.Inventory.Item.Board` interface for chassis
objects. To handle the use pattern easier, this refactors the Chassis
interface into one location and it is referenced from the needed places
(e.g. `getValidChassisPath()`).

Moreover, this part is repeated many times, which goes against best
practices.

Tested:
- GET Chassis related API and check they are the same as before
- Redfish Service Validator passes

Change-Id: Id4a51986262892c5dc81b1a3bc46fa5be7c0e9da
Signed-off-by: Myung Bae <myungbae@us.ibm.com>
diff --git a/redfish-core/lib/power.hpp b/redfish-core/lib/power.hpp
index 50e466c..1d7a59f 100644
--- a/redfish-core/lib/power.hpp
+++ b/redfish-core/lib/power.hpp
@@ -24,7 +24,6 @@
 #include <nlohmann/json.hpp>
 #include <sdbusplus/message/native_types.hpp>
 
-#include <array>
 #include <cmath>
 #include <cstddef>
 #include <cstdint>
@@ -286,12 +285,8 @@
     // This prevents things like power supplies providing the
     // chassis power limit
 
-    constexpr std::array<std::string_view, 2> interfaces = {
-        "xyz.openbmc_project.Inventory.Item.Board",
-        "xyz.openbmc_project.Inventory.Item.Chassis"};
-
     dbus::utility::getSubTreePaths(
-        "/xyz/openbmc_project/inventory", 0, interfaces,
+        "/xyz/openbmc_project/inventory", 0, chassisInterfaces,
         std::bind_front(afterGetChassis, sensorAsyncResp));
 }