[show] Fix exception error for "show ip route vrf all"

[MuLinForest]

What I did

Fix the unexpected exception error that appears when the interface is not resolved, causing the key for interfaceName to be missing in the case of static route configuration.

How I did it

Handle the case where interface_name is missing.

How to verify it

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

VRF Vrf1:
C>*192.168.1.0/24 is directly connected, Vlan1, 00:02:36
K>*192.168.1.254/32 [0/0] is directly connected, Vlan1, 00:04:54
Traceback (most recent call last):
  File "/usr/local/bin/show", line 8, in <module>
    sys.exit(cli())
  File "/usr/local/lib/python3.9/dist-packages/click/core.py", line 764, in __call__
    return self.main(*args, **kwargs)
  File "/usr/local/lib/python3.9/dist-packages/click/core.py", line 717, in main
    rv = self.invoke(ctx)
  File "/usr/local/lib/python3.9/dist-packages/click/core.py", line 1137, in invoke
    return _process_result(sub_ctx.command.invoke(sub_ctx))
  File "/usr/local/lib/python3.9/dist-packages/click/core.py", line 1137, in invoke
    return _process_result(sub_ctx.command.invoke(sub_ctx))
  File "/usr/local/lib/python3.9/dist-packages/click/core.py", line 956, in invoke
    return ctx.invoke(self.callback, **ctx.params)
  File "/usr/local/lib/python3.9/dist-packages/click/core.py", line 555, in invoke
    return callback(*args, **kwargs)
  File "/usr/local/lib/python3.9/dist-packages/click/decorators.py", line 64, in new_func
    return ctx.invoke(f, obj, *args, **kwargs)
  File "/usr/local/lib/python3.9/dist-packages/click/core.py", line 555, in invoke
    return callback(*args, **kwargs)
  File "/usr/local/lib/python3.9/dist-packages/show/main.py", line 1043, in route
    bgp_common.show_routes(args, namespace, display, verbose, "ip")
  File "/usr/local/lib/python3.9/dist-packages/show/bgp_common.py", line 474, in show_routes
    print_ip_routes(combined_route, filter_by_ip)
  File "/usr/local/lib/python3.9/dist-packages/show/bgp_common.py", line 189, in print_ip_routes
    str_2_print += get_nexthop_info_str(info[i]['nexthops'][j], False)
  File "/usr/local/lib/python3.9/dist-packages/show/bgp_common.py", line 80, in get_nexthop_info_str
    str_2_return += "(vrf {}, {},".format(nxhp_info['vrf'], nxhp_info['interfaceName'])
KeyError: 'interfaceName'

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

VRF Vrf1:
C>*192.168.1.0/24 is directly connected, Vlan1, 00:00:42
K>*192.168.1.254/32 [0/0] is directly connected, Vlan1, 00:01:45
S 192.168.2.0/24 [1/0] via 192.168.2.1 (vrf Vrf2) inactive, 00:00:28