fix: rewrite transform tests to use correct Infrahub pytest format (#20)

Rewrite all three test.yml files to use the Infrahub SDK pytest format
(version: "1.0" / infrahub_tests) instead of the previous invalid
apiVersion/kind schema. Each test file now declares a smoke_check test
(jinja2-transform-smoke) and a unit render test (jinja2-transform-unit-render)
pointing to the local input/output JSON fixtures.

Update output.json files with the actual render output from the fixed templates:
- vlan_yang: trunk_groups is null (not []) for VLANs with no trunk groups set;
  key order reflects Python dict / tojson serialization order.
- interface_yang: corrected MLAG peer-link SVI IP (10.0.199.254/31), added
  iBGP SVI IP (10.0.3.0/31), removed stale Loopback1 IP address.
- vxlan_yang: source_address now includes /32 prefix as stored in Infrahub
  IPHost fields; key order matches tojson output.

Update input.json files to be consistent with the expected output:
- vlan_yang/input.json: trunk_groups.value set to null for VLAN 40.
- interface_yang/input.json: Loopback1 ip_addresses cleared; Vlan4090 IP
  updated to 10.0.199.254/31; Vlan4091 IP added as 10.0.3.0/31.
- vxlan_yang/input.json: source_address updated to 10.0.255.11/32.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

transforms/tests/vlan_yang/output.json

@@ -1,31 +1,31 @@
 [
   {
-    "vlan_id": 40,
     "name": "test-l2-vxlan",
     "status": "ACTIVE",
-    "vlan_type": "standard",
-    "trunk_groups": [],
     "stp_enabled": true,
+    "trunk_groups": null,
+    "vlan_id": 40,
+    "vlan_type": "standard",
     "vni": 110040,
     "vni_type": "l2vni"
   },
   {
-    "vlan_id": 4090,
     "name": "mlag-peer",
     "status": "ACTIVE",
-    "vlan_type": "mlag_peer",
-    "trunk_groups": ["mlag-peer"],
     "stp_enabled": false,
+    "trunk_groups": ["mlag-peer"],
+    "vlan_id": 4090,
+    "vlan_type": "mlag_peer",
     "vni": null,
     "vni_type": null
   },
   {
-    "vlan_id": 4091,
     "name": "mlag-ibgp",
     "status": "ACTIVE",
-    "vlan_type": "mlag_ibgp",
-    "trunk_groups": ["mlag-peer"],
     "stp_enabled": false,
+    "trunk_groups": ["mlag-peer"],
+    "vlan_id": 4091,
+    "vlan_type": "mlag_ibgp",
     "vni": null,
     "vni_type": null
   }