Support MergedRef

[atootoonchianmeta]

• Update data type of nodeRef in ALSurfaceProps support both object reference and callback reference. The later is used for mergedRef
• use nodeRef if the data type of nodeRef is object

[reshadi]

I spent a bunch of time on this, but couldn't figure out any mechanism to handle the ref function callbacks AND avoid adding our own wrapper. Therefore, passing a ref function is the same as not passing ref at all and there is not much we can do differently. So, it might be better leave the code as is to signal to users we are not using it.