Add functionality to update the access token for an authenticated user

[sgmv]

We have an API for authentication. But we don't provide a mechanism for updating an access token. This functionality helps keep user to be logged.

Workflow:

1. Add the endpoint /auth/refresh
2. Send a POST request with a refresh token.
3. Return an access token from a keycloak.

DoD:

1. Functionality.
2. Updated documentation.
3. If it's possible, make any tests.