Add more fields to the user creation and add roles if they are provided

[jredrejo]

When OIDC client plugin is used in Kolibri, the very first time an user logins using an OIDC provider will trigger the creation of this user in the Kolibri database. With this plugin:

• More fields: email, birthdate and gender will be added to the user info in the database
• If a roles list is provided, the user will be added to these roles.

Closes: #3

[indirectlylit]

This looks good.

Main feedback is that the fields provided don't map perfectly to our internal models. For example birthday vs year, first/last vs full name, no support for email. This mapping would need to be defined and documented