chore: added missing file

Author: limcheekin

lib/src/surreal_extension.dart

@@ -0,0 +1,10 @@
+import 'package:surrealdb_js/surrealdb_js.dart';
+import 'package:surrealdb_wasm/surrealdb_wasm.dart';
+
+/// Wasm extension of the [Surreal] class
+extension SurrealWasm on Surreal {
+  /// Returns a new instance of the [Surreal] class with the [WasmEngine].
+  static Surreal getInstance() {
+    return Surreal({'engines': WasmEngine()});
+  }
+}