Backport the PathCapabilities API of
HADOOP-15691 as a precursor to the HADOOP-13230 backport, so making it easier to probe FS abilities.
going back further than is may be hard, but we'll see
- is depended upon by
HADOOP-17199 Backport HADOOP-13230 list/getFileStatus changes for preserved directory markers
- relates to
HADOOP-15691 Add PathCapabilities to FS and FC to complement StreamCapabilities