@CalledFromNative annotation

From https://youtrack.jetbrains.com/issue/IDEA-163737:

A very usefull annotation would be a `@CalledFromNative` that would be used to mark class methods that are meant to be called from native code. This annotation would allow for suppressing of the "method is never used" inspection and would in general help in clarifying the code. This would especially be useful in Android (Studio) projects that mix java and native code.