Is your feature request related to a problem? Please describe.
I'm interested in using MikroORM in a system where migrations and schema management are handled by another tool. I attempted to use the EntityGenerator functionality but there doesn't appear to be any way to limit entity generation to specific schemas (in this case Postgres)

Describe the solution you'd like
I'd like to b

Fireorm supports validation by leveraging the responsibility to class-validator. To perform the validation we have to declare a function on each abstract repositories like (this one or [this one](https://github.com/wovalle/fireorm/blob/dd10d7d52441894c4701a085d4