Define v3 trusts_client as library

Migrate v3 API trusts_client to tempest.lib and add unit tests for the
service client.
Partially implements blueprint consistent-service-method-names

Change-Id: I3aab5f4906718e94612e4e62a460ba13418cdc1c
diff --git a/releasenotes/notes/add-new-identity-clients-as-library-5f7ndha733nwdsn9.yaml b/releasenotes/notes/add-new-identity-clients-as-library-5f7ndha733nwdsn9.yaml
index c2742a3..7ceb9cc 100644
--- a/releasenotes/notes/add-new-identity-clients-as-library-5f7ndha733nwdsn9.yaml
+++ b/releasenotes/notes/add-new-identity-clients-as-library-5f7ndha733nwdsn9.yaml
@@ -1,12 +1,13 @@
 ---
 features:
   - |
-    Define identity service clients as libraries
+    Define identity service clients as libraries.
     Add new service clients to the library interface so the other projects can use these modules as stable libraries without
     any maintenance changes.
 
       * identity_client(v2)
       * groups_client(v3)
+      * trusts_client(v3)
       * users_client(v3)
       * identity_client(v3)
       * roles_client(v3)