[Store] Add "count" to StoreInterface

[lochmueller]

Hey everyone,

I suggest adding a count method to the StoreInterface to count the current items in the stogre.

    public function count(): int;

What do you think about it? Should I create a PR incl. the adaption of the Bridges?

Regards,
Tim

[Guikingone]

The main "issue" that I'm seeing is the redundancy with the \Countable::count() method, maybe we could extends \Countable in StoreInterface and implement the method?

[lochmueller]

@Guikingone good point. Switch to Countable interface and create a first draft as PR. I think the count is a useful add-on...