Support for Bulk DependentResource Management

[csviri]

Support of managing multiple similar resources dynamically - depending on the specs of the primary resource.

To be able to discriminate which dependent resource we are managing the desired should receive the index of the resource:

protected R desired(P primary, Context<P> context, int index) or inside the Context object. (This would require an extended Context for the dependent resources.

Questions to clarify/discuss

Should be this on top level. Thus directly the DependentResource interface should support this?. And have a wrapper dependent resource over that, that supports count? (basically agree on class level design)

Notes

• This is analogy to count in terraform, see: https://www.terraform.io/language/meta-arguments/count
• this issue closely related to an issue where an event source needs to support multiple secondary resources:
  DependentResource support for event sources where multiple resources of same type are handled for single primary #1175

[csviri]

There is some issue with linking PRs.
Original PR: #1448

See also: #1521