Implement vpd-tool object dump

[souvik1914581]

This commit implements object dump functionality in vpd-tool.
For a given Object path, the object dump functionality prints the
following properties in a JSON format to the console:
1. Present property, Pretty Name, Location Code, Sub Model
2. SN, PN, CC, FN, DR keywords under VINI record

Test:
Tested on a rainier2s2u system
root@p10bmc:~# ./vpd-tool -o -O \
/xyz/openbmc_project/inventory/system/chassis/motherboard
[
    {
        "/xyz/openbmc_project/inventory/system/chassis/motherboard": {
            "CC": "2E2D",
            "DR": "SYSTEM BACKPLANE",
            "FN": "02WG676",
            "LocationCode": "U78DA.ND0.WZS0042-P0",
            "PN": "02WG678",
            "Present": "true",
            "PrettyName": "System backplane",
            "SN": "Y131UF07302T"
        }
    }
]

root@p10bmc:~# ./vpd-tool -o -O \
/xyz/openbmc_project/inventory/system/chassis/motherboard/vdd_vrm0
[
    {
        "/xyz/openbmc_project/inventory/
        system/chassis/motherboard/vdd_vrm0": {
            "CC": "2E32",
            "DR": "CPU POWER CARD  ",
            "FN": "02CM285",
            "LocationCode": "U78DA.ND0.WZS0042-P0-C14",
            "PN": "02CM286",
            "Present": "true",
            "PrettyName": "Voltage regulator module for
                system processor module 0",
            "SN": "YH30A005M11C"
        }
    }
]

root@rain104bmctest:# ./vpd-tool -o -O "InvalidObjectPath"
root@rain104bmctest:# echo $?
255

Note: This commit does not include changes to add "type" and "TYPE" properties to the object dump. These will be added when inventory json is parsed by vpd-tool.

Screenshots below show old vpd-tool --dumpObject output vs. new vpd-tool --dumpObject output: