Add -Xjvm-defaults=all to kotlin compilations

This causes kotlinc to output default methods
instead of DefaultsImpl inner classes. It's required
for code that depends on other libraries using
@JvmDefault. It will be the default in a future
version of kotlin.

Bug: 236431222
Test: treehugger
Change-Id: I67a7cb3b816b41a441af7ec78cc64bc358c6889d