tests/user/test_users*.yml: Use extended dynamic users.json

test_users_absent.yml was using users_absent.json. It has been adapted to
use users.json instead with an additional json_query to get only the names
from users_present.json.

create_users_json.yml has been added to create users.json if it is missing
containing 500 users. It is included by test_users_present.yml and
test_users_absent.yml.

users_present.sh has been renamed to users.sh and modified to create by
default users.json with 1000 users and additional with password and
passwordexpiration in two years.

jmespath has been added to pip install list in
tests/azure/templates/playbook_tests.yml to emable the use of json_query.

The requirement for jmespath has been added to tests/README.md.