AugmentEffectiveStatementImpl should not be QNameModuleAware

This contract is not specified in yang-model-api and is a tad detrimal to the overall idea – effective augment has its children already adjusted, but notably its argument is not adjusted.

Ditch QNameModuleAware and adjust the implementation to correctly rebase its argument, if that is really what we need. Alternative approach is to use EXACT_REPLICA copy policy, in which case users of AugmentationTarget will need a bit more information – esp. parent's QName. Also AugmentationSchema may need an update to ensure its semantics matches the intent.