Can now be invoked with `./gradlew ktlintFormat`
Kotlin version is now declared in gradle.properties, due to inability to use version catalogs in settings.gradle.kts for plugins.
Fixed existing warnings, which included:
- Suppressing a deprecation warning for Java 9, as we have to maintain compatibility with Java 8 for Android
- Using a new Kotlin API introduced in Kotlin 1.5
- Removed unused local variables
Carter Jernigan