This commit comprises of 3 things:
1) Keycloak task (to bring up keycloak in teuthology inorder to execute Assume_Role_With_Web_Identity tests).
2) The required changes for this in s3tests.py which consists of writing some parameters to configuration file.
3) The yaml files which executes these tasks.
Signed-off-by: Kalpesh Pandya <kapandya@redhat.com>
