Add support for mobile loggers

[klochowicz]

At the moment we do not support showing Rust logs on mobile - it works on desktop. We could configure tracing layers that add support for native iOS/Android logging frameworks.

As a stopgap measure, we have them being piped into Dart, so they should be visible in release mode as part of FLog (our current config for Dart logging).

in the meanwhile, best debugging experience can be achieved by just using the desktop (native) target.