[TRANSLOG] Cut over to Path API

This commit also refactors `RAFReference` to work on top of a Channel instead of fetching the channel from the RandomAccessFile. The channel is created to truncate the file it opens too. This likely needs some documentation or we should allow the caller to pass the open options but I wanted to get this change out for review.
I just realized, for this log message and all of the ones below it here, we only log `index` and totally omit `reason` because there is only one `{}` in the log message...