Add QoS minimum packet rate rule client

As a preparation to test Network QoS minimum bandwidth and minimum
packet rate rules together this patch the necessary packet rate API
client to tempest lib.

blueprint: qos-minimum-guaranteed-packet-rate

Change-Id: I1c5c82e8178462652c36533093958c82b5130a55
diff --git a/releasenotes/notes/add-qos-minimum-packet-rule-client-c8bfe09873032d4a.yaml b/releasenotes/notes/add-qos-minimum-packet-rule-client-c8bfe09873032d4a.yaml
new file mode 100644
index 0000000..b65b164
--- /dev/null
+++ b/releasenotes/notes/add-qos-minimum-packet-rule-client-c8bfe09873032d4a.yaml
@@ -0,0 +1,10 @@
+---
+features:
+  - |
+    Added QoS minimum packet rate rule client:
+
+    * create_minimum_packet_rate_rule
+    * update_minimum_packet_rate_rule
+    * show_minimum_packet_rate_rule
+    * list_minimum_packet_rate_rules
+    * delete_minimum_packet_rate_rule also