Attempt to support __gc via weak-napi

[daurnimator]

In node, we may be able to support __gc via use of https://github.com/node-ffi-napi/weak-napi

[giann]

Now that weak references and finalizers are coming to v8 we can hopefully go further with this.

https://v8.dev/features/weak-references

[s-ol]

This is apparently in major browsers now as FinalizationRegistry.