Revert "[flutter_tools] move process manager into tool (#75350)" (#75639)

This reverts commit 8b6baae44c8661d548643ced73493e6a66862622.

packages/flutter_tools/lib/src/ios/xcodeproj.dart

diff --git a/packages/flutter_tools/lib/src/ios/xcodeproj.dart b/packages/flutter_tools/lib/src/ios/xcodeproj.dart
index 56cb7d7..88d1280 100644
--- a/packages/flutter_tools/lib/src/ios/xcodeproj.dart
+++ b/packages/flutter_tools/lib/src/ios/xcodeproj.dart
@@ -6,6 +6,7 @@
 
 import 'package:file/memory.dart';
 import 'package:meta/meta.dart';
+import 'package:process/process.dart';
 
 import '../artifacts.dart';
 import '../base/common.dart';