One-directional collision layer check for rigid bodies and soft bodies

[pouleyKetchoupp]

Check for each body individually if it collides with the other one or ignores it.

When a body is being ignored, the other body's mass is considered infinite when applying impulses to avoid extra overlapping.

Implements godotengine/godot-proposals#2775 for RigidBody and SoftBody.
Supersedes #49166.

[pouleyKetchoupp]

Just pushed a couple changes:

• Fix for character body collision, following Ensure KinematicBodies only interact with other Bodies with matching mask. #42641 (comment)
• Documentation update for collision_layer and collision_mask in CollisionObject2D, CollisionsObject3D, SoftBody3D.

[Calinou]

I was thinking about whether we should expose this as an opt-in project setting for 3.x. Since 3.x will remain around for a while after 4.0 is released, I think we should offer backwards-incompatible features optionally when it doesn't require too much effort.

I guess it mainly depends on how much demand there is to have this feature in 3.x. It would make porting projects to 4.x easier if you opt into the feature in 3.x.

[pouleyKetchoupp]

@Calinou That sounds like a good idea!

It should be relatively easy to do for 2D.

It would require a bit more work for 3D as we would have to make it fully compatible with Bullet as well. It's not the case for rigid body vs. rigid body collision. It should be possible, but hopefully it's not too complicated.

[reduz]

looks great!

[akien-mga]

Thanks!