update rust_builder

rust_builder/cargokit/build_tool/lib/src/build_gradle.dart

@@ -0,0 +1,49 @@
+/// This is copied from Cargokit (which is the official way to use it currently)
+/// Details: https://fzyzcjy.github.io/flutter_rust_bridge/manual/integrate/builtin
+
+import 'dart:io';
+
+import 'package:logging/logging.dart';
+import 'package:path/path.dart' as path;
+
+import 'artifacts_provider.dart';
+import 'builder.dart';
+import 'environment.dart';
+import 'options.dart';
+import 'target.dart';
+
+final log = Logger('build_gradle');
+
+class BuildGradle {
+  BuildGradle({required this.userOptions});
+
+  final CargokitUserOptions userOptions;
+
+  Future<void> build() async {
+    final targets = Environment.targetPlatforms.map((arch) {
+      final target = Target.forFlutterName(arch);
+      if (target == null) {
+        throw Exception(
+            "Unknown darwin target or platform: $arch, ${Environment.darwinPlatformName}");
+      }
+      return target;
+    }).toList();
+
+    final environment = BuildEnvironment.fromEnvironment(isAndroid: true);
+    final provider =
+        ArtifactProvider(environment: environment, userOptions: userOptions);
+    final artifacts = await provider.getArtifacts(targets);
+
+    for (final target in targets) {
+      final libs = artifacts[target]!;
+      final outputDir = path.join(Environment.outputDir, target.android!);
+      Directory(outputDir).createSync(recursive: true);
+
+      for (final lib in libs) {
+        if (lib.type == AritifactType.dylib) {
+          File(lib.path).copySync(path.join(outputDir, lib.finalFileName));
+        }
+      }
+    }
+  }
+}