Adding 2 new test cases into a zone suite

1) test_show_zone_impersonate_another_project
   Based on: "x-auth-all-projects" HTTP header
   This allows a user to impersonate another project

2) test_list_all_projects_zones
   Based on: "x-auth-all-projects:True"
   If enabled this will show results from all projects in Designate.
   Note: this test case replaced and improved "test_get_other_tenant_zone"
   as it covers more than one single tenant in its test scenario.

Change-Id: I0848299ff9f407aa7918cd12358cad4e17e71e6d
2 files changed