STR-297 :: get user on refresh

[alcalawil]

Changes summary

• I've moved all of the logic and API calls from the iframe to the SDK, so now the iFrame is just an event emitter/listener that handles user interactions and listens for SDK events. I created a custom EventEmitter class (like the Node.js ones) to propagate events so svelte components can subscribe to changes.

• I got rid of Axios (the HTTP client) because is quite difficult to make it work alongside rollup.js. As a result, we do not have all of the Axios cool features like interceptors, and timeouts. So I created a custom request interceptor for token refreshing but request timeouts are not working yet.

• I've made good improvements to the communication protocol between iframe and SDK (which is based on events). Now we can send an event and wait for a response (simulating a synchronous communication like HTTP). So the user starts a flow, the iframe sends an event to the SDK, the SDK executes business logic and API calls, gets a response from the server, and sends an event to the iframe, the iframe keeps waiting for this event until it either resolves with data or throws a timeout error.

• Now the iframe does not keep any state in localStorage or in cookies. Auth states are now managed by the SDK

To test
This is a refactor task so the app's behavior should be the same in terms of the user's perspective

1. Run api, sdk and iframe all of them on branch task/wil/str-297
2. Test every flow you can (Create User, Verify Email, New Device Verification, Login (remember to set a short JWT expiration time on the api to test the token is refreshing), Quote refreshing, Purchase Successful, Purchase Fail. Please try to test edge cases.
3. Everything should be working as usual.