Add unit test runner for autocompletion

modules/gdscript/tests/scripts/lsp/local_variables.gd

@@ -0,0 +1,25 @@
+extends Node
+
+var member := 2
+#   ^^^^^^ member -> member
+
+func test_member() -> void:
+	var test := member + 42
+	#   |  |    ^^^^^^ -> member
+	#   ^^^^ test -> test
+	test += 3
+	#<^^ -> test
+	member += 5	
+	#<^^^^ -> member
+	test = return_arg(test)
+	#  |              ^^^^ -> test
+	#<^^ -> test
+	print(test)
+	#     ^^^^ -> test
+
+func return_arg(arg: int) -> int:
+#               ^^^ arg -> arg
+	arg += 2
+	#<^ -> arg
+	return arg
+	#      ^^^ -> arg