Implied roles methods

Adds the implied roles API calls to the roles_client library:
create, get, check and delete inference rules.

This will enable the possibility to create additional identity
API tests for some features, like implied roles and domain
specific roles.

Change-Id: I1587eb862fac5b533aa4715334d54c86d9af85ff
diff --git a/releasenotes/notes/add-implied-roles-to-roles-client-library-edf96408ad9ba82e.yaml b/releasenotes/notes/add-implied-roles-to-roles-client-library-edf96408ad9ba82e.yaml
new file mode 100644
index 0000000..9116ef8
--- /dev/null
+++ b/releasenotes/notes/add-implied-roles-to-roles-client-library-edf96408ad9ba82e.yaml
@@ -0,0 +1,6 @@
+---
+features:
+  - |
+    Add the implied roles feature API to the roles_client library. This
+    feature enables the possibility to create inferences rules between
+    roles (a role being implied by another role).