Syntax Highlighting issue in `is not` operator

[Hot-key]

Godot version

4.4 stable

VS Code version

1.98.2

Godot Tools VS Code extension version

2.5.1

System information

Mac os(Darwin arm64 24.3.0)

Issue description

When using the is not operator for type checking in GDScript,
the syntax highlighting colors is and not differently,
even though is not should be treated as a single operator according to the official documentation.

Steps to reproduce

in godot editor

in vscode

# in GDscript
if node is not T:
    pass

x is Node
x is not Node

# in python
if node is not T:
    pass

x is Node
x is not Node

[Hot-key]

When using parentheses, the syntax highlighting for is not works correctly!

in vscode

in godot editor

# in GDscript
if node is not T:
    pass

x is Node
x is not Node
(x is not Node)

[henzelennard]

When parentheses are used:
'is' matches keyword.language.gdscript
'not' matches keyword.operator.wordlike.gdscript

Without paranthesis:
'is' matches storage.type.is.gdscript
'not' matches entity.name.type.class.gdscript

According to the Godot docs it seems most reasonable to introduce a dedicated is not keyword that gets matched as a full unit. However, I’m not deeply familiar with the semantics involved, so I’d appreciate a second opinion.

One potential complication: this might currently be shadowed by the class_is definition in the syntax file here.

Maybe @DaelonSuzuka can weigh in on the best approach?

@Hot-key You can check this out to see if it matches your expectations.