Low-hanging consistency fruits

[Bromeon]

This is a very cosmetic issue, and not urgent at all 🙂

The engine often uses different representations for the same thing. In some cases that's OK or would be hard to change, but in others it's a special case in codegen that may be simple to add. Just to brainstorm, doesn't mean we change all those:

Instance IDs

We have InstanceId, ObjectID (native structs, wraps u64), raw u64, raw i64, EncodedObjectAsID...

• Occurrences of instance_id
• Ideally we can replace everything with InstanceId
• Heuristic: methods ending in _instance_id that return u64 or have an id: u64 parameter.

Intly typed enums

• Object::connect_ex() takes u32, despite ConnectFlags existing.
• Signal::connect() takes i64.
• SceneTree::call_group_flags expects i64 as flag, not GroupCallFlags #185

Duplicated types in manual and generated code

We already handled some (Side, Corner, Vector2Axis, Vector3Axis), there are a few remaining:

• GDExtension.InitializationLevel vs. InitLevel
• ObjectId vs InstanceId

They don't necessarily need to be de-duplicated, but we could at least provide conversions.

Integer type proliferation

• _count methods (get/set) mostly use i32
  • unclear if usize is an option, although it's currently unsupported. Might be better to stick to i32, as it's not really inconsistent, just a bit harder to integrate with Rust.
  • What to do with all the other "index-like" APIs, see Provide feature parity for NodePath with Godot #982 (comment)
• Array::subarray_{deep|shallow} and PackedArray::subarray use usize but underlying Godot has i32, allowing wraparounds.
  • NodePath::subpath follows the same schema.
  • Considerations of making usize ranges, but allow utility to convert Godot negative-wrapped-range to convert into RangeBounds<usize>
• Signals use i32/i64
  • GraphEdit::connect_node() uses i32 ports
  • GraphEdit signal connection_request takes i64 ports