Implementing the Slot information in the PCIeDevice schema

[lakshmiy]

Redfish has moved away from the PCIeSlots schema and instead includes 
the PCIeSlot information within the PCIeDevice schema. This matches 
other Redfish schemas like Dimm or Processor.

The key highlights of this update include:
1. Integration of PCIeSlot information within the PCIeDevice schema.
        https://gerrit.openbmc.org/c/openbmc/bmcweb/+/62737
2. Inclusion of empty PCIeSlots in the PCIeDevice list, providing a 
comprehensive view of the PCIe infrastructure.
        https://gerrit.openbmc.org/c/openbmc/bmcweb/+/62073

Please note that while PCIeSlots is still present in the bmcweb, it may 
be considered for deprecation in the future as we transition to the new 
design.

Thanks,
Lakshmi Yadlapati