Add mockup files for the driver tests

UpdateService, the system's EthernetInterfaces and all chassis Sensors from public-rackmount1, unmodified.

tests/fixtures/dmtf-public-rackmount1/Chassis/1U/Sensors/PS2Frequency/index.json

@@ -0,0 +1,13 @@
+{
+    "@odata.type": "#Sensor.v1_14_0.Sensor",
+    "Id": "PS2Frequency",
+    "Name": "Power Supply #2 Frequency",
+    "ReadingType": "Frequency",
+    "Status": {
+        "State": "Absent"
+    },
+    "PhysicalContext": "PowerSupply",
+    "PhysicalSubContext": "Input",
+    "@odata.id": "/redfish/v1/Chassis/1U/Sensors/PS2Frequency",
+    "@Redfish.Copyright": "Copyright 2014-2026 DMTF. For the full DMTF copyright policy, see http://www.dmtf.org/about/policies/copyright."
+}