Do not 'prefer 32-bit' because it won't work
Breaking Change 1 of 3: Removed "db.Attempt" subclass, and moved the transactional methods to the db instance itself

- All "db.Attempt.FooAsync(...)" are now "db.FooAsync(...)"
- Simplified the FdbOperationContext object a bit
Breaking Change 2 of 3: Renamed Change() to WriteAsync() and ChangeAsync() to ReadWriteAsync()

- Change() renamed to WriteAsync() because it only take Set or Clear methods (non async)
- ChangeAsync() renamed to ReadWriteAsync() because it could also do Get, GetKey or GetRange (async)
- ReadAsync() is unchanged