Add APNS 200 metric

Author: vlbee

liveactivities/src/main/scala/com/gu/liveactivities/service/BroadcastApiClient.scala

@@ -86,7 +86,7 @@ class BroadcastApiClient(
       } else {
         val apnsUniqueId = response.headers().firstValue("apns-unique-id").orElse("not found") // SANDBOX only header for debugging
         logger.info(s"Received response with status code ${response.statusCode()} and apns-unique-id ${apnsUniqueId}")
-
+        metrics.increment(Metrics.APNS200)
         p.success(response.body())
       }
     })

liveactivities/src/main/scala/com/gu/liveactivities/util/Metrics.scala

@@ -52,6 +52,7 @@ object Metrics {
   val ChannelNotActive = "ChannelNotActive"
   val DuplicateEvent = "DuplicateEvent"
   val OutOfOrderEvent = "OutOfOrderEvent"
+  val APNS200 = "APNS200"
   val APNS4xx = "APNS4xx"
   val APNS5xx = "APNS5xx"
   val APNSNetworkError = "APNSNetworkError"