Create several building tenants

Creates up to 25 internal tenant records in order, with the same rules as the single create. Each tenant succeeds or fails on its own: the response lists one outcome per submitted tenant. A name already in the building, or already created earlier in the batch, is duplicate; a link outside the building is invalid. A request that runs out of time returns the tenants it did not reach as not_attempted: nothing was written for them, and the client sends them again.