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_slicing_pipeline_bindings.cpp

@@ -16,6 +16,8 @@ TEST_CASE("SlicingPipeline capability-type string maps round-trip", "[slicing_pi
 #include "libslic3r/Point.hpp"
 #include "libslic3r/ExPolygon.hpp"
 #include "libslic3r/Surface.hpp"
+
+#include "test_utils.hpp"
 #include "libslic3r/Layer.hpp"
 #include "libslic3r/ExtrusionEntity.hpp"
 #include "libslic3r/ExtrusionEntityCollection.hpp"
@@ -142,7 +144,7 @@ TEST_CASE("orca.slicing psGCodePostProcess context: file edit in place + config
     import_orca_module();
     py::gil_scoped_acquire gil;
 
-    const fs::path gpath = fs::temp_directory_path() / fs::unique_path("orca_pp_%%%%-%%%%.gcode");
+    ScopedTemporaryFile gpath(".gcode");
     {
         boost::nowide::ofstream ofs(gpath.string());
         ofs << "; header\nG1 X0 Y0\n";
@@ -196,9 +198,7 @@ _pp_result = Stamp().execute(_pp_ctx)
         boost::nowide::ifstream ifs(gpath.string());
         std::stringstream ss; ss << ifs.rdbuf(); contents = ss.str();
     }
-    CHECK(contents.find("; stamped by File") != std::string::npos);
-    fs::remove(gpath);
-}
+    CHECK(contents.find("; stamped by File") != std::string::npos);}
 
 // ---------------------------------------------------------------------------
 // Toolpath helpers for the raw-graph tests.