Use JWT + KV store instead of security_tokens table for

[apstanisic]

Edit: Maybe leave KV all togather, and use this solutions:

• email change confirm. Add current and next email to jwt, and only change if both match
• user invitation. We can generate password and display it to user. We will never have access to password + we'll recommend user to change it.
• Sign Up. Ne need, just check if JWT is valid and confirm
• Password reset. Add part of the hash to JWT https://stackoverflow.com/a/54865104