Added lag column to the kafka plugin

Signed-off-by: ebarrios <esteban.barrios@trivago.com>

.changeset/curvy-poems-cough.md

@@ -0,0 +1,5 @@
+---
+'@backstage/plugin-kafka': patch
+---
+
+Added lag column in the plugin main table

plugins/kafka/src/components/ConsumerGroupOffsets/ConsumerGroupOffsets.tsx

@@ -57,6 +57,17 @@ const generatedColumns: TableColumn[] = [
       return <>{row.groupOffset ?? ''}</>;
     },
   },
+  {
+    title: 'Lag',
+    field: 'lag',
+    render: (row: Partial<TopicPartitionInfo>) => {
+      let lag = undefined;
+      if (row.topicOffset && row.groupOffset) {
+        lag = +topicOffset - +groupOffset;
+      }
+      return <>{lag ?? ''}</>;
+    },
+  },
 ];
 
 type Props = {