refactor(tazjin/dns): Add zone validity checks in CI

Same as //ops/dns

Change-Id: I0399efd2e48956ec91833386adff27d94d08ef1e
Reviewed-on: https://cl.tvl.fyi/c/depot/+/3013
Tested-by: BuildkiteCI
Reviewed-by: tazjin <mail@tazj.in>

users/tazjin/dns/import

@@ -0,0 +1,12 @@
+#!/bin/sh
+set -ue
+
+# Imports a zone file into Google Cloud DNS
+readonly ZONE="${1}"
+readonly FILE="${2}"
+
+gcloud dns record-sets import "${FILE}" \
+       --project composite-watch-759 \
+       --zone-file-format \
+       --delete-all-existing \
+       --zone "${ZONE}"