Implement user provisioning on bearer token request with access token (userinfo validator)

[julien-nc]

closes #1255

When using an access token as a bearer token to make API requests, the user can't currently be properly provisioned. The authentication works but the userinfo validator does not have a provisioning strategy.

user_oidc/lib/User/Validator/UserInfoValidator.php

Line 36 in c3f4401

// TODO implement provisioning over user info endpoint

We could use the attributes we get from the userinfo endpoint to provision the user.