message: `export`: Do the export by using the install machinery
diff: namespace vcpkg::Commands::Export
  {
  + using Install::InstallDir;
  using Dependencies::ExportPlanAction;
  using Dependencies::RequestType;
  using Dependencies::ExportPlanType;
  @@ -88,6 +89,28 @@ namespace vcpkg::Commands::Export
  Checks::exit_success(VCPKG_LINE_INFO);
  }
  + Files::Filesystem& fs = paths.get_filesystem();
  + const fs::path output = paths.root / "exported";
  + std::error_code ec;
  + fs.remove_all(output, ec);
  + paths.get_filesystem().create_directory(output, ec);
  +
  + // execute the plan
  + for (const ExportPlanAction& action : export_plan)
  + {
  + const std::string display_name = action.spec.to_string();
  + System::println("Exporting package %s... ", display_name);
  +
  + const BinaryParagraph& binary_paragraph = action.any_paragraph.binary_paragraph.value_or_exit(VCPKG_LINE_INFO);
  + const InstallDir dirs = InstallDir::from_destination_root(
  + output,
  + action.spec.triplet().to_string(),
  + output / "vcpkg" / "info" / (binary_paragraph.fullstem() + ".list"));
  +
  + Install::install_files_and_write_listfile(paths.get_filesystem(), paths.package_dir(action.spec), dirs);
  + System::println(System::Color::success, "Exporting package %s... done", display_name);
  + }
  +
  Checks::exit_success(VCPKG_LINE_INFO);
  }
  }
  