Allow access to stubbed keys via the [] method.

[andrewcroome]

When using stubs, resolving :item via container.resolve(:item) returns the stub.

The small change included here ensures that container[:item] returns the stub as well.

[timriley]

I wonder if we could avoid having to add that extra alias here by changing our approach in Dry::Container::Mixin. Instead of using alias [] resolve there (alias is lexically scoped, which is why @andrewcroome has had to call it again inside the Stub module), we could just make #[] a proper method:

def [](key)
  resolve(key)
end

This should mean that the Stub mixing should work properly with #[] without the need for the additional alias, right?

[andrewcroome]

Yes, I think @timriley has the better way. I've amended this with that change.

[timriley]

@andrewcroome Fantastic, thank you!