Consider moving from jni-rs to j4rs for android

https://github.com/deviceplug/btleplug/issues/311#issuecomment-1602651285

This comment and j4rs porting POC from @trik got lost in the fray of a larger, now resolved issue. With #375 cropping up and meaning I have to look at android code again (I'm seeing that crash a *lot* through sentry), it may be time to also revisit our implementation of the java system.