Create jwt with pyjwt

[gowoons]

Purpose

Change jwt management by using pyjwt directly instead of rest simplejwt module. This allows better modularity and simplicity.

Proposal

• [x] Use jwt package instead of rest_framework_simplejwt
• [x] Generate access token
• [x] Generate refresh token
• [x] Save refresh token to session
• [x] Safely redirect to jitsi with jwt token
• [x] Implement tests

[sampaccoud]

You could add a simple test by doing that makes a GET on your endpoint and checks that the redirect is made as expected. See https://docs.djangoproject.com/en/2.0/topics/testing/tools/#django.test.SimpleTestCase.assertRedirects