Foxx repo bykey


This adds a bunch of byKey methods that reuse the byId methods. As far as I can tell, this is save, since a repository always operates on a collection. This means a key is always implicitly qualified with the collection.

Alternatively, the byId methods could support both notations of identifying a document.

I added a helper method. Since this method is meant to be internal to the repository only, I didn't add a documentation block.