Define separate inherited_roles_client for inherited roles

os-inherit APIs enables projects to inherit role assignments from either
their owning domain or projects that are higher in the hierarchy.

Currently roles_client has all the os-inherit APIs methods
but for better maintenance and readability, those should be
in separate client.

Partially implements blueprint consistent-service-method-names

Change-Id: I2d5a5699bfe85fde6219758f28f381006b21daa0
6 files changed