feat: improve session / peer storate & refactor auth flow

[Davincible]

Hey, great work on this lib!

While using it I ran into some issues, fixed a couple here.

New Session & Peer storage

• Store session by phone number, this allows you to use the same database for multiple phone numbers
• More options, to e.g. set the sql table prefix, to prevent collisions with your own tables in a project

Session storage updates might break existing storages, since I've added the phone nr field

Auth refactor

Auth flow code was a bit messy and hard to read / maintain, cleaned it up a bit

[celestix]

Hi @Davincible, Thank you for such a huge contribution! We really appreciate your efforts and time spent by you to improve the library. Your changes will be merged once they are tested and tried out by the moderators, thanks.