List all testcases within given tier

This api offers the interface to list all testcases within given tier.
All testcases within given tier will be returned.
---
tags:
  - Tiers
parameters:
  - name: tier_name
    description: tier name
    in: path
    type: string
    required: true
definitions:
  Testcases:
    type: object
    properties:
      creds_name:
          $ref: '#/definitions/Tests'
  Tests:
    type: dict
responses:
  200:
    description: List all testcases within given tier
    schema:
      $ref: '#/definitions/Testcases'
    examples:
        "tier": ""
        "testcases": []