Sticky scroll does not work with gdscript

### Godot version

v4.7.mychanges6_17.custom_build [ebcc98079]

### VS Code version

1.122.1

### Godot Tools VS Code extension version

2.7.1

### System information

Arch Linux

### Issue description

Sticky scroll is not supported. In other languages like C++ or python, the function name is stickied at the top of the screen for very long functions. Notice the line number skips from 263 to 277:

But this does not work in gdscript.

### Steps to reproduce

1. Make a very long function that extends above the top most visible line
2. Notice it is not visible anymore after scrolling down

Start by reproducing the issue in VS Code with the Godot Tools extension using a long GDScript function, following the listed steps. Then trace the extension's sticky-scroll handling for GDScript and compare it with the behavior for C++ or Python. Done means the enclosing function name remains visible while scrolling through a long GDScript function.

Written by the indexing model from the issue text.