[minigraph][port_config] Consume port_config.json while reloading minigraph

[Blueve]

What I did

Merge patch of #1705
Made additional changes for this branch.

How I did it

How to verify it

Tested on a Physical DUT with below port_config.json

[
	{
		"PORT": {
			"Ethernet48": {
				"admin_status": "down"
			}
		}
	}
]

Before

admin@str-e1031-acs-3:~$ show int status
      Interface    Lanes    Speed    MTU    Alias             Vlan    Oper    Admin    Type    Asym PFC
---------------  -------  -------  -----  -------  ---------------  ------  -------  ------  ----------
...
     Ethernet48       54      10G   9100    etp49  PortChannel0001      up       up     SFP         off
     Ethernet49       53      10G   9100    etp50  PortChannel0002      up       up     SFP         off
     Ethernet50       56      10G   9100    etp51  PortChannel0003      up       up     SFP         off
     Ethernet51       55      10G   9100    etp52  PortChannel0004      up       up     SFP         off
PortChannel0001      N/A      10G   9100      N/A           routed      up       up     N/A         N/A
PortChannel0002      N/A      10G   9100      N/A           routed      up       up     N/A         N/A
PortChannel0003      N/A      10G   9100      N/A           routed      up       up     N/A         N/A
PortChannel0004      N/A      10G   9100      N/A           routed      up       up     N/A         N/A

admin@str-e1031-acs-3:~$ show ip bgp sum
...
Neighbor        V         AS MsgRcvd MsgSent   TblVer  InQ OutQ Up/Down  State/PfxRcd
10.0.0.57       4 64600     501     475        0    0    0 00:17:33      902
10.0.0.59       4 64600     501      23        0    0    0 00:17:37      902
10.0.0.61       4 64600     501     475        0    0    0 00:17:34      902
10.0.0.63       4 64600     501     474        0    0    0 00:17:31      902

After

admin@str-e1031-acs-3:~$ show int status
      Interface    Lanes    Speed    MTU    Alias             Vlan    Oper    Admin    Type    Asym PFC
---------------  -------  -------  -----  -------  ---------------  ------  -------  ------  ----------
...
     Ethernet48       54      10G   9100    etp49  PortChannel0001    down     down     SFP         off
     Ethernet49       53      10G   9100    etp50  PortChannel0002      up       up     SFP         off
     Ethernet50       56      10G   9100    etp51  PortChannel0003      up       up     SFP         off
     Ethernet51       55      10G   9100    etp52  PortChannel0004      up       up     SFP         off
PortChannel0001      N/A      10G   9100      N/A           routed    down       up     N/A         N/A
PortChannel0002      N/A      10G   9100      N/A           routed      up       up     N/A         N/A
PortChannel0003      N/A      10G   9100      N/A           routed      up       up     N/A         N/A
PortChannel0004      N/A      10G   9100      N/A           routed      up       up     N/A         N/A
admin@str-e1031-acs-3:~$ show ip bgp sum
...
10.0.0.57       4 64600       0       0        0    0    0 never    Idle       
10.0.0.59       4 64600     484       6        0    0    0 00:00:30      902
10.0.0.61       4 64600     484     457        0    0    0 00:00:28      902
10.0.0.63       4 64600     484     255        0    0    0 00:00:30      902

Previous command output (if the output of a command-line utility has changed)

New command output (if the output of a command-line utility has changed)

[lgtm-com]

This pull request fixes 1 alert when merging 79cfd21 into c235153 - view on LGTM.com

fixed alerts:

• 1 for Unused import