[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 wonder if we should extend `ChannelReference` to implement `Closeable` and have the `.close()` method decrement the ref and throw an error if it's not now at 0 (which it should be since it's being closed in this case). That way we error immediately if the translog is closed but something incremented the channel ref.

What do you think of this? Dunno if you think it might make ChannelReference too complex.