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/plugin_test_utils.hpp

@@ -6,6 +6,8 @@
 
 #include <string>
 
+#include "test_utils.hpp"
+
 namespace Slic3r {
 
 // Point data_dir() at a throwaway directory for the lifetime of a test and
@@ -13,24 +15,20 @@ namespace Slic3r {
 // disposable tree and tests don't leak state into each other.
 struct ScopedDataDir
 {
+    ScopedTemporaryDir        tmp;   // owns the temp dir (create + recursive remove)
+    boost::filesystem::path   dir;   // = tmp.path(); kept as a member for callers
     std::string               previous;
-    boost::filesystem::path   dir;
 
     explicit ScopedDataDir(const std::string& tag)
+        : tmp("orca-" + tag), dir(tmp.path()), previous(data_dir())
     {
-        namespace fs = boost::filesystem;
-        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;
-        boost::filesystem::remove_all(dir, ec);
-    }
+    ~ScopedDataDir() { set_data_dir(previous); } // tmp removes the directory
+
+    // The plugin manager scans {data_dir}/orca_plugins.
+    boost::filesystem::path plugins_dir() const { return dir / "orca_plugins"; }
 
     ScopedDataDir(const ScopedDataDir&)            = delete;
     ScopedDataDir& operator=(const ScopedDataDir&) = delete;