Add tests to cover policy_minimum_bandwidth_rule

This patch set adds tests to cover the policy_minimum_bandwidth_rule API [0].
Test creates, showes, updates and deletes policy_minimum_bandwidth_rule.
Part of "Increase Neutron RBAC Coverage" initiative [1]

[0] https://developer.openstack.org/api-ref/network/v2/index.html#qos-minimum-bandwidth-rules
[1] https://storyboard.openstack.org/#!/story/2002641

Change-Id: Ice4d20d20320f70ea0a8332bb53f1ebcde2c7a84
Depends-On: https://review.openstack.org/#/c/592762/
Story: 2002641
Task: 22321
1 file changed