Replace QuickHull with Bullet's convex hull computer.

The code is based on the current version of thirdparty/vhacd and modified to use Godot's types and code style.

Additional changes:
- backported and extended PagedAllocator to allow leaked objects
- applied patch from https://github.com/bulletphysics/bullet3/pull/3037

servers/physics/shape_sw.cpp

@@ -31,8 +31,8 @@
 #include "shape_sw.h"
 
 #include "core/image.h"
+#include "core/math/convex_hull.h"
 #include "core/math/geometry.h"
-#include "core/math/quick_hull.h"
 #include "core/sort_array.h"
 
 // HeightMapShapeSW is based on Bullet btHeightfieldTerrainShape.
@@ -1090,9 +1090,9 @@ Vector3 ConvexPolygonShapeSW::get_moment_of_inertia(real_t p_mass) const {
 }
 
 void ConvexPolygonShapeSW::_setup(const Vector<Vector3> &p_vertices) {
-	Error err = QuickHull::build(p_vertices, mesh);
+	Error err = ConvexHullComputer::convex_hull(p_vertices, mesh);
 	if (err != OK)
-		ERR_PRINT("Failed to build QuickHull");
+		ERR_PRINT("Failed to build convex hull");
 
 	AABB _aabb;