IGBP: Address inconsistent flatten/unflatten for QueueBufferInput

Conversion.cpp uses flatten/unflatten to convert between
::IGraphicBufferProducer::QueueBufferInput and
::hardware::graphics::bufferqueue::V1_0::IGraphicBufferProducer::QueueBufferInput.

But because those 2 classes have different definitions, add the code to
handle them.

Test: libgui_test
Bug: 192439037
Change-Id: Ief0ece787912da981de273da89c9247798f83bf3