Add Missing Includes Across src/libslic3r

Every libslic3r source and header now directly includes the headers declaring what it uses, rather than relying on the precompiled header or transitive includes. Generated with clang-tidy misc-include-cleaner, with libslic3r headers spelled libslic3r/... so they resolve outside the library's private include paths. MultiMaterialSegmentation.hpp, Support/SupportParameters.hpp and Format/STEP.hpp are made self-contained by hand.

src/libslic3r/MinAreaBoundingBox.cpp

@@ -1,5 +1,12 @@
 #include "MinAreaBoundingBox.hpp"
+#include "Point.hpp"
+#include "libslic3r.h"
 
+#include <cstdint>
+#include "libnest2d/common.hpp"
+#include <cmath>
+#include <cstdlib>
+#include "libnest2d/geometry_traits.hpp"
 #include <libslic3r/ExPolygon.hpp>
 
 #if defined(_MSC_VER) && defined(__clang__)