[pyreverse] Fix duplicate arrows when class attribute is assigned more than once

[pranav-data]

Type of Changes

	Type
✓	:bug: Bug fix
	:sparkles: New feature
	:hammer: Refactoring
	:scroll: Docs

Description

Postprocessing relationships and classes to find replication across relationship types / attributes.

Output for example:

classDiagram
  class A {
    var : int
  }
  class B {
    a_obj
    func()
  }
  A --* B : a_obj

Closes #9267 Closes: #8046 Fixes closed issue: #8189