Update GDScript $ node reference tokenization

[YofiAsi]

Issue
In the current TextMate grammar for GDScript, the $ symbol used for node references (e.g., $Label) is incorrectly tokenized as keyword.control.flow.gdscript. This causes the symbol to be highlighted with the same color as flow control keywords like if and while, which is semantically incorrect.

Changes
This PR changes the tokenization of the $ node reference symbol from keyword.control.flow.gdscript to constant.character.escape.gdscript in all three relevant patterns:

• builtin_get_node_shorthand_quoted
• builtin_get_node_shorthand_bare
• builtin_get_node_shorthand_bare_multi

Benefits

• More semantically accurate token classification
• Better visual distinction between flow control keywords and node references
• Consistent highlighting for node path references in GDScript
• Improves readability for developers using the VSCode extension

Testing
I've verified these changes with multiple color themes to ensure the highlighting is now consistent and appropriate for this language feature.

[DaelonSuzuka]

The highlighting of $ (and %) is not a mistake.