Add GDScript submodule and syntax test file for GDScript support, see #XXX (@chetanjangir0)

Author: chetanjangir0

.gitmodules

@@ -266,3 +266,6 @@
 [submodule "assets/syntaxes/02_Extra/Idris2"]
 	path = assets/syntaxes/02_Extra/Idris2
 	url = https://github.com/buzden/sublime-syntax-idris2
+[submodule "assets/syntaxes/02_Extra/GDScript-sublime"]
+	path = assets/syntaxes/02_Extra/GDScript-sublime
+	url = https://github.com/beefsack/GDScript-sublime

CHANGELOG.md

@@ -22,6 +22,7 @@
 - Map `ndjson` extension to JSON syntax, see #3209 (@keith-hall)
 - Map files with `csproj`, `vbproj`, `props` and `targets` extensions to XML syntax, see #3213 (@keith-hall)
 - Add debsources syntax to highlight `/etc/apt/sources.list` files, see #3215 (@keith-hall)
+- Add syntax test file for GDScript highlighting, see #XYZ (@chetanjangir0)
 
 ## Themes
 

assets/syntaxes/02_Extra/GDScript-sublime

@@ -0,0 +1,71 @@
+extends Node
+
+signal custom_signal(param)
+
+const PI = 3.14159
+
+var untyped_var = "Hello, World!"
+var typed_int: int = 42
+var typed_float: float = 3.14
+var typed_string: String = "GDScript Test"
+var typed_array: Array = [1, 2, 3, 4]
+var typed_dict: Dictionary = {"key": "value", "number": 100}
+
+onready var label = $Label
+
+func say_hello() -> void:
+	print("Hello from GDScript!")
+
+func add_numbers(a: int, b: int = 10) -> int:
+	return a + b
+
+func process_value(value: int) -> String:
+	if value < 0:
+		return "Negative"
+	elif value == 0:
+		return "Zero"
+	else:
+		return "Positive"
+
+func sum_array(arr: Array) -> int:
+	var total: int = 0
+	for num in arr:
+		total += num
+	return total
+
+func describe_number(num: int) -> String:
+	match num:
+		0:
+			return "Zero"
+		1, 2, 3:
+			return "Small number"
+		_:
+			return "Large number"
+
+func long_description() -> String:
+	return """This is a test file for GDScript.
+It covers variables, functions, control structures, loops, signals, inner classes,
+multiline strings, arrays, and dictionaries."""
+
+class InnerExample:
+	var inner_value: int = 99
+	func show_value() -> void:
+		print("Inner value is:", inner_value)
+
+func test_inner_class() -> void:
+	var inner = InnerExample.new()
+	inner.show_value()
+
+func trigger_signal() -> void:
+	emit_signal("custom_signal", "TestParam")
+
+func _ready() -> void:
+	say_hello()
+	var result_add = add_numbers(5)
+	print("Add result:", result_add)
+	print("Process value for -5:", process_value(-5))
+	print("Sum of array [10, 20, 30]:", sum_array([10, 20, 30]))
+	print("Description for 2:", describe_number(2))
+	print("Long description:\n", long_description())
+	test_inner_class()
+	trigger_signal()