[Feature]: API client can assign a space role to a user with POST /v3/roles

[gcapizzi]

Background

As an admin
I want to assign space roles to users
So that I can control permissions in the space

Acceptance Criteria

GIVEN a space exists
AND a user other than the admin exists
AND a ClusterRole exists
WHEN I make the following request:

curl "https://api.example.org/v3/roles" \
  -X POST \
  -H "Content-Type: application/json" \
  -d '{
      "type": "<the ClusterRole name>",
      "relationships": {
        "user": {
          "data": {
            "guid": "<the username>"
          }
        },
        "space": {
          "data": {
            "guid": "<the space GUID>"
          }
        }
      }
    }'

THEN I get the following response:

HTTP/1.1 201 Created
Content-Type: application/json

{
   "guid": "40557c70-d1bd-4976-a2ab-a85f5e882418",
   "created_at": "2019-10-10T17:19:12Z",
   "updated_at": "2019-10-10T17:19:12Z",
   "type": "<the ClusterRole name>",
   "relationships": {
      "user": {
         "data": {
            "guid": "<the username>"
         }
      },
      "space": {
         "data": {
            "guid": "<the space GUID>"
         }
      },
      "organization": {
         "data": null
      }
   },
   "links": {
      "self": {
         "href": "https://api.example.org/v3/roles/40557c70-d1bd-4976-a2ab-a85f5e882418"
      },
      "space": {
         "href": "https://api.example.org/v3/spaces/05c5da3b-6cbc-421c-87c3-20bb3c41ab7c"
      }
   }
}

AND I see a RoleBinding in the space namespace for the specified user

Dev Notes

• POST /v3/roles