Revert "Vendor package:tar and package:chunked_stream (#2932)" (#2940)

This reverts commit 255a309.

Author: sigurdm

analysis_options.yaml

@@ -1,7 +1,6 @@
 include: package:pedantic/analysis_options.yaml
 
 analyzer:
-  exclude: [lib/src/third_party/**]
   errors:
     unused_import: error
     unused_local_variable: error

lib/src/io.dart

@@ -15,13 +15,12 @@ import 'package:path/path.dart' as path;
 import 'package:pedantic/pedantic.dart';
 import 'package:pool/pool.dart';
 import 'package:stack_trace/stack_trace.dart';
+import 'package:tar/tar.dart';
 
 import 'error_group.dart';
 import 'exceptions.dart';
 import 'exit_codes.dart' as exit_codes;
 import 'log.dart' as log;
-// ignore: avoid_relative_lib_imports
-import 'third_party/tar/lib/tar.dart';
 import 'utils.dart';
 
 export 'package:http/http.dart' show ByteStream;