Cleaning up and optimizing scene-graph-material and scene-graph-renderer

Cleaning up and optimizing scene-graph-material and scene-graph-renderer

Previously we would update each materials status through renderers.
This means that if same material was used by 10 renderers, it would be processed and prepared 10 times

This patch changes the following:
- Materials are prepared as a separate update step
- Renderer asks its material for ready (=can be rendered) and complete (=has finished resouce loading) status
- CompleteStatusManager is removed
- Resource manager handles status of loaded images and whether FBOs have been rendered to (i.e. they can be considerer "loaded")
- GL Trackers are only used for NativeImages as GL guarantees the sync of texture FBOs, they are synchronized as soon as they are bound as texture
- glSyncAbstraction no longer passed to update, Render tasks create sync object if & when needed and RenderManager initiliazes them
- BitmapMetadata changed to simpler POD so Dali::Vector can be used
- Deleted lots of unnecessary containers of trackers and complicated logic to handle them

Change-Id: I654b9d16cd0a225eabd0897441c5e8dd4b8b0398