"Target Surface:" and "Source Mesh:" should only accept nodes that inherit Node3D

[Stronkkey]

Godot version

4.1.3 stable.arch_linux

System information

Artix Linux Godot v4.1.3 stable.arch_linux

Issue description

Both "Target Surface:" and "Source Mesh:" accept non Node3D nodes which doesn't really make any sense as they need 3D geometry to function.

Steps to reproduce

1. Add a MultiMeshInstance3D
2. Add a Node that doesn't inherit Node3D
3. Open the "Populate Surface" menu and click the right button of either "Target Surface:" or "Source Mesh:"

Minimal reproduction project

N/A

[Calinou]

• Related to "Create Emission Points From Node" doesn't filter out non Node3D nodes when it should. #84889.

The actual restriction is MeshInstance3D for both fields, not "just" Node3D.