libcamera: buffer: Move captured metadata to FrameMetadata

Move the metadata retrieved when dequeuing a V4L2 buffer into a
FrameMetadata object. This is done as a step to migrate to the
FrameBuffer interface as the functions added to Buffer around
FrameMetadata match the ones in FrameBuffer.

Signed-off-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

src/libcamera/request.cpp

@@ -238,7 +238,7 @@ bool Request::completeBuffer(Buffer *buffer)
 
 	buffer->request_ = nullptr;
 
-	if (buffer->status() == Buffer::BufferCancelled)
+	if (buffer->metadata().status == FrameMetadata::FrameCancelled)
 		cancelled_ = true;
 
 	return !hasPendingBuffers();