Add Ordinal enum value in PolarisEventType

[adnanhemani]

That's a valid concern. I'm OK to remove it as this is preview feature, but it requires notice. Another option is to adding code field to explicitly set a number for the type. This is more robust so that it prevents any developer adding an event in the middle and accidentally break downstreams. It isn't a blocker for this PR though. Can you file an issue for this?

Something like:

public enum EventType {
    AFTER_UPDATE(101),
    AFTER_DELETE(102);

    private final int code;

    EventType(int code) {
        this.code = code;
    }

    public int code() {
        return code;
    }
}

Adding a constructor will prevent accidental ordinal changes and make future evolution safer. Given the downstream relies on the event type, I think it's reasonable to add a explicit code.

Originally posted by @flyrain in #3195 (comment)