Refactor terminal and remove duplicate code.

lib/terminal/models/js_log_data.dart

@@ -0,0 +1,15 @@
+class JsLogData {
+  JsLogData({
+    required this.level,
+    required this.args,
+    this.stack,
+    this.context,
+    this.contextRequestId,
+  });
+
+  final String level; // log | warn | error | fatal
+  final List<String> args;
+  final String? stack;
+  final String? context; // preRequest | postResponse | global
+  final String? contextRequestId;
+}