[VarDumper] polymorphic and stateless output setter

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | -
| License       | MIT
| Doc PR        | https://github.com/symfony/symfony-docs/pull/4243

While writing the documentation on the VarDumper component, it came to me that selecting the output destination was a state-full process for streams.
This PR fixes that by allowing not only callbacks but also streams on the second argument of `AbstractDumper::dump()`.
I also updated some interfaces to make the feature more straightforward.