I've been working on a little project that uses D1 and have been hoping that is how D1 will evolve. A db per customer in my case. Is the colocation in a durable object so 'business logic' and sqlite can live in the same isolate for performance and security? Would that be a post 'out of beta' feature? Ive been building as a monolith thinking that the number of databases in the alpha was indicative of the future.