S3A empty dir markers are not created in s3guard as authoritative

Newly created empty dirs, or markers created after delete operations, are not marked in S3Guard as auth. This has adverse consequences in that following changes (i.e. new files) don't get marked as auth either...it needs a listFiles call to scan the source and mark as auth.

I could stick a quick fix in to HADOOP-16697, but don't want to as I don't like what that would mean. Essentially, finishedWrite() need to recognise when an empty directory markers being created (it does this already) and then always declare it as auth.

I'd prefer for the mkdirs operation to pass a flag all the way through to finishedWrite so that it doesn't need to infer this. The WriteOpContext of HADOOP-16134 would be the way to do this. Yes it's a big change but it would be extensible -and I already have some plans there.

Instead it will be a follow-up.

The tests for this problem are part of HADOOP-16697, just disabled for now.