Modify IP space support check on edge gateway

[rocknes]

Previously, we assumed that each org vdc edge gateway can be connected to one provider gateway and hence have only 1 uplink. Recently, a customer issue has uncovered that it is indeed possible for an edge gateway to have multiple uplinks. One of the uplink will be the uplink to Provider Gateway, while rest would be uplink to NSX-T imported external networks.

in this PR, we are modifying the check to test IP space support on an edge gateway to ignore all NSX-T import network uplinks and only use the Provider gateway uplink for determination of IP space support.

Testing done: On a fresh VCD 10.5 testbed,

• We created two provider gateways.
• First gateway supports ip space, the second one doesn't.
• We also created an external network from existing NSX-T segment and assigned it to provider gateway 1.
• We created two edge gateways, one of them connected to the first provider gateway and the other one connected to the second provider gateway.
• We created two org vdc networks connected to these edge gateways (individually).
• Verified using POSTman that the gateway supporting IP Spaces has two uplinks

  GET https://w4-hs10-priv-32-146.eng.vmware.com/cloudapi/1.0.0/edgeGateways
  .
  .
          "edgeGatewayUplinks": [
              {
                  "uplinkId": "urn:vcloud:network:947c0a7a-50f9-4080-a6cc-3bdd497db67a",
                  "uplinkName": "provider_gw",
                  .
                  "usingIpSpace": true,
                  .
                  "backingType": "NSXT_TIER0"
              },
              {
                  "uplinkId": "urn:vcloud:network:66a40a09-fe85-451a-b754-ade4fe9dbd24",
                  "uplinkName": "test-net",
                  .
                  .
                  "usingIpSpace": false,
                  .
                  "backingType": "IMPORTED_T_LOGICAL_SWITCH"
              }

• Ran the IP space test : TestGatewayUsingIpSpaces

/usr/local/go/bin/go tool test2json -t /Users/sena/Library/Caches/JetBrains/GoLand2023.3/tmp/GoLand/___10TestGatewayUsingIpSpaces_in_github_com_vmware_cloud_provider_for_cloud_director_pkg_vcdsdk.test -test.v -test.paniconexit0 -test.run ^\QTestGatewayUsingIpSpaces\E$
=== RUN   TestGatewayUsingIpSpaces
I0723 15:05:03.953622    6042 auth.go:50] Using VCD OpenAPI version [37.2]
I0723 15:05:05.092706    6042 auth.go:74] Running module as sysadmin [false]
I0723 15:05:05.512544    6042 client.go:201] Client is sysadmin: [false]
I0723 15:05:06.506108    6042 gateway.go:70] Obtained Gateway [provider_vdc_edge] for Network Name [provider_orgvdc_net] of type [NSXT_FLEXIBLE_SEGMENT]
I0723 15:05:07.639639    6042 gateway.go:70] Obtained Gateway [provider_org_edge_no_ipspace] for Network Name [provider_orgvdc_net_no_ipspace] of type [NSXT_FLEXIBLE_SEGMENT]
--- PASS: TestGatewayUsingIpSpaces (3.78s)
PASS