feat: Spit role from assignment provider

[gtema]

In python Keystone roles and assignments are part of the same module,
but they implement different provider APIs. It is also possible to have
both providers managed by different drivers (i.e. roles from sql while
assignments from OPA or OpenFGA).

Closes: #537

[github-actions]

🦢 Load Test Results

Goose Attack Report

Plan Overview

Action	Started	Stopped	Elapsed	Users
Increasing	26-02-17 16:06:44	26-02-17 16:06:46	00:00:02	0 → 4
Maintaining	26-02-17 16:06:46	26-02-17 16:07:16	00:00:30	4
Decreasing	26-02-17 16:07:16	26-02-17 16:07:16	00:00:00	0 ← 4

Request Metrics

Method	Name	# Requests	# Fails	Average (ms)	Min (ms)	Max (ms)	RPS	Failures/s
GET		8016	0	14.47	8	49	267.20	0.00
	Aggregated	8016	0	14.47	8	49	267.20	0.00

Response Time Metrics

Method	Name	50%ile (ms)	60%ile (ms)	70%ile (ms)	80%ile (ms)	90%ile (ms)	95%ile (ms)	99%ile (ms)	100%ile (ms)
GET		12	13	19	19	20	21	22	49
	Aggregated	12	13	19	19	20	21	22	49

Status Code Metrics

Method	Name	Status Codes
GET		8,016 [200]
	Aggregated	8,016 [200]

Transaction Metrics

Transaction	# Times Run	# Fails	Average (ms)	Min (ms)	Max (ms)	RPS	Failures/s
ListUsers
0.0	0	0	0.00	0	0	0.00	0.00
0.1	5050	0	11.42	8	42	168.33	0.00
ValidateToken
1.0	0	0	0.00	0	0	0.00	0.00
1.1	2966	0	19.80	15	49	98.87	0.00
Aggregated	8016	0	14.47	8	49	267.20	0.00

Scenario Metrics

Transaction	# Users	# Times Run	Average (ms)	Min (ms)	Max (ms)	Scenarios/s	Iterations
ListUsers	2	5048	11.42	8	42	168.27	2524.00
ValidateToken	2	2964	19.80	16	49	98.80	1482.00
Aggregated	4	8012	14.52	8	49	267.07	4006.00

View full report