Update build setup to Gradle 8 and compileSdk 34

This project could use an update to the build setup, which would make it easier to work with and probably faster to build.

Here is what I think should be done:

• Upgrade Gradle to 8.1+
• Upgrade the Android Gradle Plugin to 8.0+
• Upgrade Kotlin to 1.8+
• Use Gradle Version Catalogs
• Check if all the custom gradle tooling is necessary, replace with something more standard if possible

Let me know if you want help with that, I'll gladly send a merge request.