[Android] Replace Guava with Kotlin Stdlib usages

[tyvsmith]

Investigate if we can remove guava in favor of kotlin stdlib

Usages:

❯ agc "import com.google.common.base.*" | sort | uniq
import com.google.common.base.Charsets;
import com.google.common.base.Joiner
import com.google.common.base.Optional
import com.google.common.base.Preconditions;