With this PR we remove allmost all custom macro's to create the multiple
database type code. This is now handled by Diesel it self.
This removed the need of the following functions/macro's:
- `db_object!`
- `::to_db`
- `.from_db()`
All `conn` variables do not need a `mut` anymore (says nightly rust)
It is also possible to just use one schema instead of multiple per type.
It looks like either something changed in the latest v2023.8.x versions,
or when using Biometrics to login, but the MasterPasswordHash is an
optional value during the Approve action.
This PR makes the MasterPasswordHash an optional value which resolves
this issues. Bitwarden works the same way.
I also changed the EncKey to an Option in the database since empty
strings as a default value is not nice in databases, better to use
`null` in these cases.
Fixes#3819