Add ability to sync in both ways

[Nafania]

As from what i see - for now this component syncs data only in one way - from google keep to ha shopping list.
It doesn't sync anything in other way, i.e. from ha shopping list to google keep.

It would be great to have sync in both ways.

My scenario is the following - im using google keep as grocery list when im not in home. But in home im using voice automation which are integrated into ha shopping list. So i prefer to keep shopping list in one place - google keep.