[Feature Request] Add impulse information to Stride.Physics.ContactPoint

[Oberon-Zheng]

As Stride API indicated, Stride.Physics.ContactPoint gets collision information in simulation via an internal method LatestContactPointsFor(), in which ContactPoint obtains the contact data in a buffer and returned with Bullet Native API (to be elaborative, it's from btManifoldPoint/ManifoldPoint in BulletSharp).

stride/sources/engine/Stride.Physics/Simulation.cs

Lines 493 to 506 in 4c46fdc

	for (int j = 0; j < numContacts; j++)
	{
	var point = BulletSharp.ManifoldPoint.FromPtr(btPersistentManifold_getContactPoint(persManifoldPtr, j));
	buffer.Add(new ContactPoint
	{
	ColliderA = collA,
	ColliderB = collB,
	Distance = point.m_distance1,
	Normal = point.m_normalWorldOnB,
	PositionOnA = point.m_positionWorldOnA,
	PositionOnB = point.m_positionWorldOnB,
	});
	}
	}

Since it's found that Stride ContactPoint provides limited contact info about collider, normalvec, distance and point pos. But other game engines can also provide the impulse of contact (e.g., in Unity, we can get this via ContactPoint.impulse field, in Godot we can find this via get_contact_impulse of PhysicsServer), which is missing in Stride API but actually supported in BulletSharp.ManifoldPoint (point.m_appliedImpulse).

stride/sources/engine/Stride.Physics/ContactPoint.cs

Lines 11 to 39 in 4c46fdc

	public struct ContactPoint : IEquatable<ContactPoint>
	{
	public PhysicsComponent ColliderA;
	public PhysicsComponent ColliderB;
	public float Distance;
	public Vector3 Normal;
	public Vector3 PositionOnA;
	public Vector3 PositionOnB;
	public bool Equals(ContactPoint other)
	{
	return ((ColliderA == other.ColliderA && ColliderB == other.ColliderB)
	|| (ColliderA == other.ColliderB && ColliderB == other.ColliderA))
	&& Distance == other.Distance
	&& Normal == other.Normal
	&& PositionOnA == other.PositionOnA
	&& PositionOnB == other.PositionOnB;
	}
	public override bool Equals(object obj) => obj is ContactPoint other && Equals(other);
	public override int GetHashCode()
	{
	return HashCode.Combine(ColliderA, ColliderB, Distance, Normal, PositionOnA, PositionOnB);
	}
	}

AFAIAC, sometimes this impulse information is useful for physics interaction manipulation, so it's probably necessary reasonable to provide this in ContactPoint since the underlying Bullet body is literally not accessible directly as internal member of RigidbodyComponent.