Add dozens of new integration tests to the GDScript test suite

This also ignores `.out` files in the file format static checks.

modules/gdscript/tests/scripts/parser/features/dictionary_mixed_syntax.gd

@@ -0,0 +1,12 @@
+func test():
+	# Mixing Python-style and Lua-style syntax in the same dictionary declaration
+	# is allowed.
+	var dict = {
+		"hello": {
+			world = {
+				"is": "beautiful",
+			},
+		},
+	}
+
+	print(dict)