Send events wrapped in unique_ptr to InputConsumerCallbacks

This will allow the upper layers to release the ownership and hand the
object over to the ndk client. The client will then assume the
ownership. This is not possible with the current implementation of
rvalue, because the ndk interface is only using pointers.

Unfortunately, this makes things more clunky for tests (unless we modify
BlockingQueue).

Bug: 324271765
Test: TEST=libinput_tests; m $TEST && $ANDROID_HOST_OUT/nativetest64/$TEST/$TEST --gtest_repeat=100 --gtest_break_on_failure
Change-Id: I0cf326a22f840be6f8aa00d1e69f818815788487