GC features

Is it possible to use GC features like struct or array from wasmtime-py?

```python
from wasmtime import Store, Module, Instance, Config, Engine
config = Config()
config.wasm_gc = True
engine = Engine(config)
store = Store(engine)
module = Module(store.engine, """
(module
(type $point (struct (field $x i64) (field $y i64)))
(func $myadd (export "myadd") (param i32 i32) (result i32)
(local.get 0)
(local.get 1)
(i32.add)
)
)
""")
```

```
struct indexed types not supported without the gc feature (at offset 0xb)
```