refactor: group up types related to servers

striker-ui/types/AnvilServers.d.ts

@@ -1,8 +1,10 @@
+declare type AnvilServer = {
+  server_name: string;
+  server_uuid: string;
+  server_state: string;
+  server_host_index: number;
+};
+
 declare type AnvilServers = {
-  servers: Array<{
-    server_name: string;
-    server_uuid: string;
-    server_state: string;
-    server_host_index: number;
-  }>;
+  servers: Array<AnvilServer>;
 };