Kill Kotlin process before R8 tasks

[kaeawc]

Based on Inaki's research https://dev.to/cdsap/what-happens-when-you-kill-the-kotlin-daemon-before-r8-el7 we should look into and implement integrating his Gradle plugin R8Booster

Applying the plugin should automatically register a killKotlinCompileDaemon task and have R8 tasks depend on it ensuring Kotlin compile daemons are killed before R8 runs.