Contacts DB needs love

[fare]

• Many attempts to add-identity result in failure with *** ERROR IN std/db/dbi#sql-exec -- sqlite-exec: [sql-error] SQLite error: constraint failed at which point a parasitic anonymous contact is created. TODO: figure out the error, have better error message, use transaction to make the failure atomic.
• You can't add a contact address without an identity(!)

The entire contacts database needs a bit of love.

[fare]

I started a notion document for re-designing the contacts db:
https://www.notion.so/mukn/Contact-DB-design-93f714e1cb6946209e3103e6b61e894e

As for how to represent the data on disk, I also started another notion document for how I think we should or shouldn't persist data:
https://www.notion.so/mukn/Glow-Persistence-65aedf3fee1542b1975b614538010cf1