membrane: Consider a Symbol.hasInstance distortion for the instanceof operator

I was initially surprised a few days ago [when testing instanceof across object graphs](https://github.com/ajvincent/es-membrane/blob/7891c99e316d642fe0786bc2e67cbe68136d961b/projects/v2-es-membrane/membranes_decorated/spec/concepts.ts#L220).

Very quickly I realized this is probably technically correct: I wrap every value in the "wet" graph before calling methods. But it's quite non-intuitive. Also, a bit unsupported: if you're outside the membrane and can interact with the graphs directly as I did in this test, then occasionally weird behaviors are going to happen.

I don't exactly know what I should do about this, if anything, but I'm filing this as a reminder.