Add support for 7Zip to the packaging script. (#13659)

A modern version of 7Zip (7za.exe) is now installed on the bots, this makes use of that.

dev/bots/prepare_package.dart

@@ -65,7 +65,7 @@ class ArchiveCreator {
   final ProcessRunner _runner;
   String flutter;
   final String git = Platform.isWindows ? 'git.bat' : 'git';
-  final String zip = Platform.isWindows ? 'zip.exe' : 'zip';
+  final String zip = Platform.isWindows ? '7za.exe' : 'zip';
   final String tar = Platform.isWindows ? 'tar.exe' : 'tar';
   Map<String, String> environment;
 
@@ -154,13 +154,17 @@ class ArchiveCreator {
   }
 
   void createZipArchive(File output, Directory source) {
-    final List<String> args = <String>[
-      '-r',
-      '-9',
-      '-q',
+    final List<String> args = <String>[];
+    if (Platform.isWindows) {
+      // We use 7-Zip on Windows, which has different args.
+      args.addAll(<String>['a', '-tzip', '-mx=9']);
+    } else {
+      args.addAll(<String>['-r', '-9', '-q']);
+    }
+    args.addAll(<String>[
       output.absolute.path,
       path.basename(source.absolute.path),
-    ];
+    ]);
 
     _runProcess(zip, args,
         workingDirectory: new Directory(path.dirname(source.absolute.path)));

dev/bots/test/prepare_package_test.dart

@@ -21,7 +21,7 @@ void main() {
     List<MockProcessResult> results;
     final List<List<String>> args = <List<String>>[];
     final List<Map<Symbol, dynamic>> namedArgs = <Map<Symbol, dynamic>>[];
-    final String zipExe = Platform.isWindows ? 'zip.exe' : 'zip';
+    final String zipExe = Platform.isWindows ? '7za.exe' : 'zip';
     final String tarExe = Platform.isWindows ? 'tar.exe' : 'tar';
     final String gitExe = Platform.isWindows ? 'git.bat' : 'git';
     String flutterExe;
@@ -135,8 +135,13 @@ void main() {
         '$flutterExe create --template=package ${path.join(tmpDir.path, 'create_package')}',
         '$flutterExe create --template=plugin ${path.join(tmpDir.path, 'create_plugin')}',
         '$gitExe clean -f -X **/.packages',
-        '$zipExe -r -9 -q ${path.join(tmpDir.path, 'flutter_master.zip')} flutter',
       ];
+      if (Platform.isWindows) {
+        commands.add('$zipExe a -tzip -mx=9 ${path.join(tmpDir.path, 'flutter_master.zip')} flutter');
+      } else {
+        commands.add('$zipExe -r -9 -q ${path.join(tmpDir.path, 'flutter_master.zip')} flutter');
+      }
+
       int step = 0;
       for (String command in commands) {
         _verifyCommand(args[step++], command);