Support logging to a stream

[blaix]

We currently have Db.withLogFile : Permission -> Path -> Connection -> Connection that appends logs to the file.

What I really wanted was a way to log to a Stream.Writable Bytes but there's currently no way to open a file as a writable stream without overwriting the contents of the file. Once we support that, I can add Db.withLogStream. Then you can log to a file, stdout, or whatever you want.