Adding server evacuate client

This patch adds compute server evacuate API client method.

This client method is required to implement evacuate related tests
in OpenStack Patrole project.

Change-Id: Ie0d65d83923331caaa9cbbbd63b096ff8400bffa
Partial-Bug:: #1673811
diff --git a/releasenotes/notes/add-compute-server-evaculate-client-as-a-library-ed76baf25f02c3ca.yaml b/releasenotes/notes/add-compute-server-evaculate-client-as-a-library-ed76baf25f02c3ca.yaml
new file mode 100644
index 0000000..848a21b
--- /dev/null
+++ b/releasenotes/notes/add-compute-server-evaculate-client-as-a-library-ed76baf25f02c3ca.yaml
@@ -0,0 +1,3 @@
+---
+features:
+    - Define the compute server evacuate client method in the servers_client library.