Improve collision generation usability in the new 3D scene import workflow.

With this PR it's possible to add a collision during the Mesh import, directly in editor.
To generate the shape is possible to chose between the following options:
- Decompose Convex: The Mesh is decomposed in one or many Convex Shapes (Using the VHACD library).
- Simple Convex: Is generated a convex shape that enclose the entire mesh.
- Trimesh: Generate a trimesh shape using the Mesh faces.
- Box: Add a primitive box shape, where you can tweak the `size`, `position`, `rotation`.
- Sphere: Add a primitive sphere shape, where you can tweak the `radius`, `position`, `rotation`.
- Cylinder: Add a primitive cylinder shape, where you can tweak the `height`, `radius`, `position`, `rotation`.
- Capsule: Add a primitive capsule shape, where you can tweak the `height`, `radius`, `position`, `rotation`.

It's also possible to chose the generated body, so you can create:
- Rigid Body.
- Static Body.
- Area.

scene/resources/mesh.h

@@ -159,11 +159,42 @@ public:
 	Size2i get_lightmap_size_hint() const;
 	void clear_cache() const;
 
-	typedef Vector<Vector<Face3>> (*ConvexDecompositionFunc)(const Vector<Face3> &p_faces, int p_max_convex_hulls);
+	struct ConvexDecompositionSettings {
+		enum Mode : int {
+			CONVEX_DECOMPOSITION_MODE_VOXEL = 0,
+			CONVEX_DECOMPOSITION_MODE_TETRAHEDRON
+		};
+
+		/// Maximum concavity. [Range: 0.0 -> 1.0]
+		real_t max_concavity = 1.0;
+		/// Controls the bias toward clipping along symmetry planes. [Range: 0.0 -> 1.0]
+		real_t symmetry_planes_clipping_bias = 0.05;
+		/// Controls the bias toward clipping along revolution axes. [Range: 0.0 -> 1.0]
+		real_t revolution_axes_clipping_bias = 0.05;
+		real_t min_volume_per_convex_hull = 0.0001;
+		/// Maximum number of voxels generated during the voxelization stage.
+		uint32_t resolution = 10'000;
+		uint32_t max_num_vertices_per_convex_hull = 32;
+		/// Controls the granularity of the search for the "best" clipping plane.
+		/// [Range: 1 -> 16]
+		uint32_t plane_downsampling = 4;
+		/// Controls the precision of the convex-hull generation process during the
+		/// clipping plane selection stage.
+		/// [Range: 1 -> 16]
+		uint32_t convexhull_downsampling = 4;
+		/// enable/disable normalizing the mesh before applying the convex decomposition.
+		bool normalize_mesh = false;
+		Mode mode = CONVEX_DECOMPOSITION_MODE_VOXEL;
+		bool convexhull_approximation = true;
+		/// This is the maximum number of convex hulls to produce from the merge operation.
+		uint32_t max_convex_hulls = 1;
+		bool project_hull_vertices = true;
+	};
+	typedef Vector<Vector<Face3>> (*ConvexDecompositionFunc)(const Vector<Face3> &p_faces, const ConvexDecompositionSettings &p_settings);
 
 	static ConvexDecompositionFunc convex_composition_function;
 
-	Vector<Ref<Shape3D>> convex_decompose(int p_max_convex_hulls = -1) const;
+	Vector<Ref<Shape3D>> convex_decompose(const ConvexDecompositionSettings &p_settings) const;
 
 	virtual int get_builtin_bind_pose_count() const;
 	virtual Transform3D get_builtin_bind_pose(int p_index) const;