Add jni_uses_platform_api property to android_app

Add a jni_uses_platform_api property that will be used to allow
an app that builds against the SDK to use JNI libraries that build
against platform APIs.  For now it is a noop, but the next CL will
make it enforcing.

Bug: 149591057
Test: m checkbuild
Change-Id: Id7b7c8186bf0e28498a4cfb15c6a6ccc95df3679