Re-include BBS's Clipperutils2 (#11415)

* Clipper2 from BBS

* Fix

* Clipper2 Update: 1.5.2 -> 2.1.5.4

* Replace Clipper2Lib::Area calls with Clipper2LibArea

Updated area calculation calls to use Clipper2LibArea<T> instead of Clipper2Lib::Area<T> in multiple locations. This change likely reflects a refactor or renaming of the area calculation function.

* Revert "Replace Clipper2Lib::Area calls with Clipper2LibArea"

This reverts commit c92a9a1522e8d7b0f1f8557d4c752a8b8c8fc279.

* Revert "Clipper2 Update: 1.5.2 -> 2.1.5.4"

This reverts commit a745894bdc9cda4ce4d19e0705d214b78091acad.

* Update project version

src/libslic3r/CMakeLists.txt

@@ -92,6 +92,8 @@ set(lisbslic3r_sources
     clipper.hpp
     ClipperUtils.cpp
     ClipperUtils.hpp
+    Clipper2Utils.cpp
+    Clipper2Utils.hpp
     ClipperZUtils.hpp
     Color.cpp
     Color.hpp
@@ -578,6 +580,7 @@ target_link_libraries(libslic3r
         boost_libs
         cereal::cereal
         clipper
+        Clipper2
         eigen
         glu-libtess
         JPEG::JPEG