Handle non-enumerable/writable/configurable properties

[Rich-Harris]

Currently, devalue will ignore non-enumerable properties. It could use Object.getOwnPropertyDescriptors instead and handle those, correctly setting writable, enumerable and configurable.

With that, { foo: 1 } would just be the (common) special case where writable, enumerable and configurable are all true.

At the same time, we would throw on getters and setters, since devalue doesn't serialize functions.