Port "Add target" from the Swift Package Manager code base to SwiftRefactor

Author: DougGregor

Sources/SwiftRefactor/CMakeLists.txt

@@ -24,6 +24,7 @@ add_swift_syntax_library(SwiftRefactor
 
   PackageManifest/AbsolutePath.swift
   PackageManifest/AddPackageDependency.swift
+  PackageManifest/AddTarget.swift
   PackageManifest/AddTargetDependency.swift
   PackageManifest/ManifestEditError.swift
   PackageManifest/ManifestEditRefactoringProvider.swift
@@ -34,6 +35,7 @@ add_swift_syntax_library(SwiftRefactor
   PackageManifest/RelativePath.swift
   PackageManifest/SemanticVersion.swift
   PackageManifest/SourceControlURL.swift
+  PackageManifest/StringUtils.swift
   PackageManifest/SyntaxEditUtils.swift
   PackageManifest/TargetDescription.swift
 )