Far forward ZDC calibrations json

Somehow this doesn't feel in the right place here, when it should be in ip6...

calibrations/ffi_zdc.json

+{
+    "ffi_zdc_ecal": {
+        "sampling_fraction": 1.0,
+    },
+    "ffi_zdc_hcal": {
+        "sampling_fraction": 1.0,
+    },
+}