[GameTest] Add a way to access actor properties

Add a way to read/write to actor properties. I know there are already dynamic properties, but dynamic properties can't be used in client-side Molang.

const property = entity.getActorProperty("namespace:my_actor_property");

property.value; // returns the current value of the property (read-only)

property.type; // returns the type of the property (read-only)

property.validValues; // returns an array of valid values for the property (read-only)

property.clientSync; // returns the `client_sync` value in the property definition (read-only)

property.set(value); // sets the property to `value`. Will throw if `value` is not one of `property.validValues`