Add built-in batching support to Repository `save` and `remove` overloads

[patroza]

Background:

Adapters like CosmosDB do not support more than 100 items in a batch.
However when batching, one breaks the transactional properties (one batch may succeed, while another fails).
As such we've left this to the user to explicitly enable.

This however makes it more verbose to do this and repeat it. As such, we should add a batch option: batch?: true | number
with the default being not defined = no batching.
The option should be documented to break transactional properties, so that the user is aware and can adjust approach.

For overloads that support ...items, we could use currying, first passing the settings, then the items.