Clean up crystal-db proxy methods with correct usage

Nobody has claimed this yet.

https://github.com/luckyframework/avram/blob/519213e5c5f6a7a61766d16e815a2f6220500cae/src/avram/database.cr#L87-L123

Using these low-level crystal-db methods give a false sense of unified code in how they work. For example, it *looks* like you can do this, but you can't...

```crystal
# assume this returns a single SpecialModel
AppDatabase.query(sql, args: [1], as: SpecialModel)

# assume this returns an Array(SpecialModel)
AppDatabase.query_all(sql, args: [1], as: SpecialModel)
```

The issue here is that `query` actually returns a `ResultSet` which could either be a single record or an array of records... There's no `as:` named arg for `query`.

Ref: https://github.com/will/crystal-pg/issues/202

The reason we map these though is so we can properly log them through Avram (and Dexter). I'm sure there's other wrong uses in here, but they should all be cleaned up.

Start in src/avram/database.cr at lines 87-123 and compare each proxy with the crystal-db and crystal-pg usage described in the issue and linked reference. Check that the proxies use correct method signatures while retaining Avram and Dexter logging; done means the incorrect mappings and other wrong uses in this section are cleaned up.

Written by the indexing model from the issue text.