glsinkbin: validate property in internal sink

It might be the case that glgsinkbin would try to set a property to its internal sink which doesn't exist in it, leading to a glib's warning. For example, when playsink sets 'force-aspect-ratio' property and glsinkbin has, as internal sink, appsink, which doesn't handle that property.

The patch validates the incoming property to forward to internal sink if it exists in the internal sink and both properties has the same type.