Add a ans_tmp_clean option to delete old ~/.ansible/tmp sub-directories

The ~/.ansible/tmp directory can accumulate a lot of old unneeded data, a optional ans_tmp_clean option that can be set to a time period, eg:

ans_tmp_clean: 1w

Which is converted to seconds using the to_seconds_filter and then directories that are sub-directories of ~/.ansible/tmp that are older than this are then deleted.

Or when set to:

ans_tmp_clean: never

The tasks are skipped.