src: migrate from deprecated SnapshotCreator constructor

[joyeecheung]

Previously we have been using the variant of SnapshotCreator that only passes the external references instead of v8::Isolate::CreateParams and it's about to be deprecated. Switch to using the new constructor that takes a fully CreateParams instead.

This also makes sure that the snapshot building script is using the Node.js array buffer allocator instead of a separate default one that was previously used by the old constructor. The zero fill toggle in the Node.js array buffer allocator would still be ignored during snapshot building, however, until we fixes the array buffer allocator and let V8 own the toggle backing store instead, because otherwise the snapshot would contain the external toggle address and become unreproducible.