test: finish the temp-file cleanup (#14976)

Follow-up to #14785. Routes the tests that still hand-rolled temp paths through
the shared helpers and unifies the temp guards.

- Add ScopedTemporaryDir and a shared ScopedTemporaryPath base under it and
  ScopedTemporaryFile.
- Move test_3mf's round-trip .3mf output out of the TEST_DATA_DIR source tree
  (a fixed-name leak) and test_toolordering's fixed-name temp .gcode (a sharding
  collision) onto ScopedTemporaryFile.
- Move test_config, test_slicing_pipeline_bindings, the test_3mf backup dirs, and
  test_preset_bundle_loading onto the guards.
- Make slic3rutils ScopedDataDir compose ScopedTemporaryDir; dedupe
  test_network_versions' fixture and delete test_plugin_lifecycle's duplicate.

tests/slic3rutils/test_plugin_lifecycle.cpp

@@ -6,6 +6,8 @@
 #include <slic3r/plugin/PluginFsUtils.hpp>
 #include <slic3r/plugin/PythonInterpreter.hpp>
 
+#include "plugin_test_utils.hpp"
+
 #include <boost/filesystem.hpp>
 
 #include <algorithm>
@@ -25,32 +27,6 @@ namespace fs = boost::filesystem;
 
 namespace {
 
-// Point data_dir() at a throwaway directory for the lifetime of a test and restore the previous
-// value afterwards, so discovery scans a disposable {data_dir}/orca_plugins tree and tests don't
-// leak state into each other.
-struct ScopedDataDir
-{
-    std::string previous;
-    fs::path    dir;
-
-    explicit ScopedDataDir(const std::string& tag)
-    {
-        previous = data_dir();
-        dir      = fs::temp_directory_path() / fs::unique_path("orca-" + tag + "-%%%%-%%%%");
-        fs::create_directories(dir);
-        set_data_dir(dir.string());
-    }
-
-    ~ScopedDataDir()
-    {
-        set_data_dir(previous);
-        boost::system::error_code ec;
-        fs::remove_all(dir, ec);
-    }
-
-    fs::path plugins_dir() const { return dir / "orca_plugins"; }
-};
-
 // Brings the plugin system up, and tears it down explicitly at the end of the test.
 //
 // Shutting the interpreter down here, rather than leaving it to PythonInterpreter's static