collect and show mqtt state for nodes

prisma/migrations/20240331045118_add_mqtt_connection_state_columns_to_nodes_table/migration.sql

@@ -0,0 +1,3 @@
+-- AlterTable
+ALTER TABLE `nodes` ADD COLUMN `mqtt_connection_state` VARCHAR(191) NULL,
+    ADD COLUMN `mqtt_connection_state_updated_at` DATETIME(3) NULL;

prisma/schema.prisma

@@ -36,6 +36,9 @@ model Node {
   neighbours                        Json?
   neighbours_updated_at             DateTime?
 
+  mqtt_connection_state            String?
+  mqtt_connection_state_updated_at DateTime?
+
   created_at DateTime @default(now())
   updated_at DateTime @default(now()) @updatedAt