EX-8130 lipe: Add func for working with paths

EX-8130 lipe: Add func for working with paths

This patсh adds directory path processing helper functions
that will be used later to collect directory size statistics.

These functions set the stage for working on increasing the
size counters for each directory, along the entire chain in
the file or directory path.

Test-Parameters: trivial
Signed-off-by: Vitaliy Kuznetsov <vkuznetsov@ddn.com>
Change-Id: I6e7302e9771dce2933c6730a1117fec3bc2b0fda
Reviewed-on: https://review.whamcloud.com/c/ex/lustre-release/+/53961
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Alexandre Ioffe <aioffe@ddn.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>