SurfaceUpdate coming before BeginRendering breaks A2UI V0.8 rendering

[sugoi-yuzuru]

Possible bug when surfaceUpdate is returned BEFORE beginRendering.

I see a console error property accessing for null when A2UI surface is rendered. The reason is because the Surfaces returned from the MessageProcessor includes Surfaces that were created from surfaceUpdate message yet haven't received the corresponding beginRendering message. The renderer throws an error when surfaceRootId is not provided.

Since the out-of-order A2UI DataPart response is by-design, we should apply some filtering logic to the v0.8 MessageProcessor to filter out surfaces that do not have SurfaceRootId property yet.