Allow substatement-derived state to be inherited

TreeAwareEffectiveStatements are deriving QName->EffectiveStatement maps from substatements of a particular statement.

With YANGTOOLS-1212 we get to reuse the substatement file, but that is not enough – we need to pass the previous effective instance to StatementFactory, so that its implementation can extract derived state – i.e. those maps.

Also update all implementations to pass this derived state around.