Update java-spaghetti.

[Dirbaio]

Opening as draft for visibility and because I wanted to see what it looks like. It gets rid of that unsafe lifetime upgrade which is nice :)

This isn't quite ready for prime-time because it needs feature(arbitrary_self_types). It's supposed to be stabilized Soon(TM) because it's high on Rust's priorities because Rust-for-Linux needs it. I'm not sure whether to release the new java-spaghetti without waiting for it or not though. Would you be OK with bluest on Android requiring nightly until then?