Adds short-lived JWT authentication to the `/deposit` and `/withdraw` interactive flows. Also adds an integration point for providing deposit instructions for users after initiating a deposit request through their wallet.
Other changes:
- Renamed `to_address` and `from_address` JSON response fields to `to` and `from`
- Created `PolarisSameSiteMiddleware` to be installed in your `settings.MIDDLEWARE`
- Removed the unnecessary `/confirm_transaction` endpoint