Fix CollisionObject3D parameter shadowing

[Sauermann]

resolve godotengine/godot-proposals#5715

The signal input_event parameter position shadows the property Node3D.position.
For a better usability, change the parameter name as suggested in that proposal.

Updated 2023-07-05: Virtual function _input_event has the same problem. Fix it also for that function.

[AThousandShips]

Wanting the dotnet team to take a look concerning renaming and compatibility, I forget the specifics on what constitutes breaking compatibility there (as this is a non-critical change)

[raulsntos]

This changes the parameter name of a signal and a virtual method.

• Changing parameter names of signals doesn't break compat in C#.
  We generate a delegate for the C# event, when used like this users can't invoke it so it won't break compat.
  To subscribe to these events, the lambda parameters can use whatever name the user wants.
• Changing parameter names of virtual methods doesn't break compat in C# for implementers.
  The override can use different parameter names, although it's recommended to use the same ones as the original declaration.
• Changing parameter names of methods breaks source compat in C# for callers if the call-site was using named parameters (e.g: MyMethod(position: myPosition)).
  But I'd say this is uncommon for these virtual methods that are only meant to be called by the engine, and source compat is not a very disruptive break so I think it's OK to break compat here.

[Sauermann]

Superseded by #89721