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/warnings/deprecated_operators.gd

@@ -0,0 +1,8 @@
+func test():
+	# `and` should be used instead.
+	if true && true:
+		pass
+
+	# `or` should be used instead.
+	if false || true:
+		pass