Look into ways to support #private field access defined by Nodes

[drborges]

By default, #private fields are not forwarded by proxies in JS. That's because a proxy is technically still another object that cannot access private context within another object.

There's a chance this will be a limitation in Arbor where devs may have to shy away from #private fields, or when using TypeScript rely on TS's private access modifier since after compilation these don't become #private fields.

However, if there's a way we can provide a workaround so Arbor can support #private fields seamlessly or in a simple way (again, the whole point of Arbor is to have a very thin API so devs can mostly rely on their JS knowledge) that'd be ideal.

Worst case scenario we'll just document this as one of the tradeoffs of using Arbor.