breaking sqlcipher usage update

[neonphog]

Summary

• upgrade rusqlite
• pin cipher_compatibility to version 4
• apply ios workaround
• track salt in config, and pragma as consequence of ios workaround

TODO:

• CHANGELOG(s) updated with appropriate info

[ThetaSinner]

There's a test for migration that will open the newly encrypted database with the same compatibility settings right?

Just thinking ahead to when we move versions and only remember to update one :)

[neonphog]

Yes. In fact the workflow is:

• to try to open the database
• on error, run this encrypt_unencrypted_database function
• then re-run the normal open the database command

So it ends up testing itself : )

[neonphog]

(and yes, there's a migrate_unencrypted test that triggers this code to be run.)

[ThetaSinner]

I've had a look at the sqlcipher docs and I think I understand what this is doing. Looks good to me!