[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 definitely think it's worth adding an explanation of `reuseExisting` to the javadocs for this constructor, when I see "reuseExisting" I don't expect it to truncate an existing file, so we should be very careful with documenting this.