Gradle samples for Kotlin/Native

The following samples are avaliable:

• export-kotlin-multiplatform - Exporting Kotlin/Native dependencies in a framework using the kotlin-multiplatform Gradle plugin.
• export-kotlin-platform-native - Exporting Kotlin/Native dependencies in a framework using the org.jetbrains.kotlin.platform.native Gradle plugin.
• debug-logger - Using different source code in release and debug binaries.
• fat-framework - Building a universal framework for iOS x64, arm32 and arm64.