Build macOS via workspace, rather than project (#33198)

This is necesasry to integrate CocoaPods, since CocoaPods operates
primarily on the workspace rather than the project.

packages/flutter_tools/lib/src/macos/build_macos.dart

@@ -38,7 +38,7 @@ Future<void> buildMacOS(FlutterProject flutterProject, BuildInfo buildInfo) asyn
     '/usr/bin/env',
     'xcrun',
     'xcodebuild',
-    '-project', flutterProject.macos.xcodeProjectFile.path,
+    '-workspace', flutterProject.macos.xcodeWorkspace.path,
     '-configuration', '$config',
     '-scheme', 'Runner',
     '-derivedDataPath', flutterBuildDir.absolute.path,

packages/flutter_tools/lib/src/project.dart

@@ -571,6 +571,8 @@ class MacOSProject {
 
   final FlutterProject project;
 
+  static const String _hostAppBundleName = 'Runner';
+
   bool existsSync() => project.directory.childDirectory('macos').existsSync();
 
   Directory get _editableDirectory => project.directory.childDirectory('macos');
@@ -582,7 +584,10 @@ class MacOSProject {
   File get generatedXcodePropertiesFile => _cacheDirectory.childFile('Generated.xcconfig');
 
   /// The Xcode project file.
-  Directory get xcodeProjectFile => _editableDirectory.childDirectory('Runner.xcodeproj');
+  Directory get xcodeProject => _editableDirectory.childDirectory('$_hostAppBundleName.xcodeproj');
+
+  /// The Xcode workspace file.
+  Directory get xcodeWorkspace => _editableDirectory.childDirectory('$_hostAppBundleName.xcworkspace');
 
   /// The file where the Xcode build will write the name of the built app.
   ///

packages/flutter_tools/test/commands/build_macos_test.dart

@@ -75,7 +75,7 @@ void main() {
       '/usr/bin/env',
       'xcrun',
       'xcodebuild',
-      '-project', flutterProject.macos.xcodeProjectFile.path,
+      '-workspace', flutterProject.macos.xcodeWorkspace.path,
       '-configuration', 'Debug',
       '-scheme', 'Runner',
       '-derivedDataPath', flutterBuildDir.absolute.path,