Upgrade several of the things.
* Upgrade Kotlin to match the version used by Briar, to fix Briar's mailbox integration tests * Upgrade Hilt for compatibility with Kotlin 1.9 * Upgrade Android Gradle Plugin so that R8 can understand metadata produced by Kotlin 1.9 * Upgrade Java version (and thus JVM requirement for building) to match the version used by Kotlin I also upgraded Jackson while getting JacksonProguardTest to pass, which may or may not have been necessary (upgrading AGP may have been what did the trick).