Find usages does not work for built-in modules/functions

[derkork]

Describe the bug I can find the usages of my own functions and modules but not the ones of built-ins.

To Reproduce Steps to reproduce the behavior:

1. Create a custom module.
2. Use the module somewhere.
3. Right-click on the usage - you see an entry "find usages of "
4. Create an "echo" node.
5. Right-click on the node.
6. You don't see a "find usages of "echo"" menu entry.

Expected behavior Usage search works for all modules and functions, not just custom ones.

Desktop (please complete the following information):

• OS: Windows 11
• Version of OpenSCAD Graph Editor: 0.9.3