GDScript Ampersand & StringName not in grammar documentation

**Your Godot version:**
4.3

**Issue description:**
Seems in grammar there isn't a rule to detect ampersand with string (stringName), to detect something like:
```gdscript
if event.is_action_pressed(&"click"):
```
versus
```gdscript
if event.is_action_pressed("click"):
```
I think it could be used in linters to add a warning with litterals.

**URL to the documentation page (if already existing):**
https://docs.godotengine.org/en/latest/contributing/development/file_formats/gdscript_grammar.html
And documentation explaining StringName
https://docs.godotengine.org/en/latest/classes/class_stringname.html#class-stringname