Add new parameter `tenant_name_discovery`

Add new parameter `tenant_name_discovery`

Enabling this parameter will identify user and project
names from the polled metrics [1].

These details are collected by making additional requests
to keystone service, depending upon the scale of environment,
number of projects/users and the count of metrics polled in
every iteration, enabling this could overwhelm the keystone
service.

[1] Iee5dbf09a1fd3ac571746fc66d2683eb8e6a1b27

Conflicts:
	manifests/agent/polling.pp

Depends-On: https://review.opendev.org/877647
Signed-off-by: Yadnesh Kulkarni <ykulkarn@redhat.com>
Change-Id: I045c7cd7a86d0f7f97a9078cbfc74353dcff0eb8
(cherry picked from commit b00000fb86e2882c11fb399d9adf410812a895bd)