Fix GImpact algo registration issue

[kvasnevskyivlad]

After I updated the version of Bullet to the latest one, I noticed that GImpact collision functionality, namely contactPairTest doesn't work anymore. So after some time, I found out this discussion - #3747 with a reference to this commit 9ee1c4e. I noticed that with that commit were introduced two "kinds" of algos:

enum ebtDispatcherQueryType
{
	BT_CONTACT_POINT_ALGORITHMS = 1,
	BT_CLOSEST_POINT_ALGORITHMS = 2
};

and by default, we use BT_CLOSEST_POINT_ALGORITHMS. But in the registerAlgorithm method in btGImpactCollisionAlgorithm.cpp, the GImpact algorithm is registered only as BT_CONTACT_POINT_ALGORITHMS, so if you call contactPairTest, it doesn't work.

I am not sure whether my fix is correct, but it works for me, so to fix it, I added registration for BT_CLOSEST_POINT_ALGORITHMS as well.