[3.x] Store ObjectID instead of Object * for Shape Owners

[timothyqiu]

3.x version of #57182

[lawnjelly]

Codewise it looks ok to me, so there is mainly just any performance implications to look at, I saw the ObjectDB is using a hashmap and don't know how fast it is. I guess it would be good to check nothing here is getting hit in a hot loop in e.g. physics, as there might be an alternate strategy if that were the case.

shape_owner_get_transform() doesn't seem to be used outside the editor from core (but is bound).
shape_owner_get_owner() is used from

KinematicCollision2D::get_local_shape
KinematicCollision2D::get_collider_shape

KinematicCollision::get_local_shape
KinematicCollision::get_collider_shape

I'm not absolutely sure on this, it looks like they are just bound so probably ok (maybe a physics guy could confirm this, or at least a 2nd pair of eyes).

I'm also having no idea how fast Hashmap is, if it is O (1) then then should be fine. I'm kind of not sure why it is a Hashmap rather than a Handle Pool, maybe the IDs of Godot objects increasing is required for some reason.

[timothyqiu]

I'm also having no idea how fast Hashmap is, if it is O (1) then then should be fine.

Hashmap is O(1) if there is no hash collision. When there is, it'll go through a linear search among entries that have the same hash value.

[lawnjelly]

As far as I can see is ok. I can't see any evidence of it being performance sensitive.

[akien-mga]

Thanks!

[akien-mga]

Cherry-picked for 3.4.3.