Create the D-Bus inventory object for terminus base on the Top most Container type.

[ThuBaNguyen]

As the comment in the discussion https://gerrit.openbmc.org/c/openbmc/pldm/+/73250/comment/b4c1d025_c2637f93/

> how are we sure that the remove end point is just a board ? and no something like a motherboard ?
I think the correct inventory paths for items under the overall system should all be /xyz/openbmc_project/ivventory/system/<item_type>/<item_name> (like most inventory paths on OpenBMC do). <item_type> should depend on EntityType of the PDR, which can be somehow mapped 1:1 with PDI's Item list https://github.com/openbmc/phosphor-dbus-interfaces/tree/master/yaml/xyz/openbmc_project/Inventory/Item.

Ex: for Board (EntityID 60), the object path should be /xyz/openbmc_project/inventory/system/board/<item_name>, and interface should be Inventory.Item.Board.

Right now, I think we should hardcode it first to /xyz/openbmc_project/inventory/system/board/<item_name>, and interface Inventory.Item.Board so that one terminus can be reported as one chassis instance in Redfish chassis collection (/redfish/v1/Chassis/) and have sensors reported on Redfish. Then have a mapping to deal with each entity type later.

The pldmd code should support create the inventory object for terminus base on the entity type of the items under the overall system.