JWT Setup for Authentication - ios App feature

[xihai01]

What github issue is this PR for, if any?

This PR will set up the JWT authentication as part of the ios app codethechange is building.
It isn't linked to any issue in this repo - we forked a copy of this repo and are working on that forked copy.
Now we want to merge what we have done for the authentication.

What changed, and why?

Set up JWT with Devise.
I had to extend Devise sessions controller's create action to return a custom response for JSON requests.
I also extend respond_to_on_destroy method so sign out responds in json.
Additionally, I had to modify the accessible module so JSON requests don't get redirected to the root path.

How is this tested? (please write tests!) 💖💪

I created request specs for good/bad login to verify correct headers were sent (e.x authorization, content-type...etc) and also JSON data.
I also made specs for the sign out route -> testing JWT is moved to denylist and a 200 response.
Postman was used to make changes (i.e unassign a case assignment) in the portal provided a JWT was present.
I also did a live test where I ran the rails server on a ngrok tunnel and frontend app using expo go side by side.
See screenshots below.

Screenshots please :)

Live test using Ngrok and my android phone running the frontend with Expo go.

Postman: Success login means auth JWT in header

Postman: Failed login means auth JWT not in header

Postman: Unassign a case assignment using auth token passed in request header

Postman: Unassign a case assignment with no auth token

Postman: Sign out returns 200 response + JWT is moved to denylist

Feedback please? (optional)

We are very interested in your feedback! Please give us some :) https://forms.gle/1D5ACNgTs2u9gSdh9

[compwron]

seems reasonable. :) @FireLemons how does it look to you?

[FireLemons]

🥇