Add missing v2 token related testcases

We have added scenarios to test_validate_token_head(),
test_validate_token() and test_validate_revoke_token()

Change-Id: I9a781e3062b3d86cfb2d846b10437453bcb6a56e
Co-Authored-By: Nishant Kumar <nk613n@att.com>
Co-Authored-By: Pradeep Kumar <pk5294@att.com>
Depends-On: Idc351fdcce420bb42c00bab23460f32e3c66e9ce
Closes-Bug: #1689262
3 files changed