[v3] Show detail of an quota in API os-quota-sets

nova-manage shows `in_use`, `reserved` including `limit` of a quota.
So create a new API named `detail` to do the same with nova-manage.

The new URL is like :/v3/os-quota-sets/1234/detail.

Fix bug: #1183870

DocImpact

Change-Id: Ic53a68acf0f3f3184c7a900360343bb576560f46
Merge "[v3] Show detail of an quota in API os-quota-sets"