feat: improve repository decorator

[nikophil]

improve RepositoryDecorator based on

RepositoryProxy / RepositoryDecorator

• [x] RepositoryProxy was iterable
• [x] $repository->find([]); used to not throw exceptions

Here is something about RepositoryDecorator I don't know how to mititgate, and which creates hard failures in my code base:

• [ ] in 2.0, RepositoryDecorator only returns T but RepositoryProxy used to return Proxy<T>. I don't know how we should do for this? On one hand I'd prefer it to not return proxy. On the other hand, I don't know how we can deprecate this, or inform users.

[kbond]

RepositoryDecorator only returns T but RepositoryProxy used to return Proxy.

Yeah, I wanted to simplify this in 2.0 so that you only get a proxy if you use the static PersistentProxyObjectFactory methods.

What about a config option? repository_proxy: true, we throw a deprecation if true forcing users to set to false in 1.x. Then in 2.x, we deprecate this config option entirely.