Implement tempest client for keystone v2 token APIs

Implement Tempest client for Keystone v2 token API - v2.0/tokens/

Although some of the APIs have been implemented, many of the token
related APIs are yet to be implemented such as
list_endpoints_for_token, check_token_existence

Here are the OpenStack docs link
https://developer.openstack.org/api-ref/identity/v2-admin/index.html
https://developer.openstack.org/api-ref/identity/v2/

Change-Id: Idc351fdcce420bb42c00bab23460f32e3c66e9ce
Co-Authored-By: Pramod Kumar Singh <pk110e@att.com>
Co-Authored-By: Nishant Kumar E <nk613n@att.com>
5 files changed