LU-17814 utils: implement real pfind

LU-17814 utils: implement real pfind

This patch does the last step of integrating the actual
find code with pfind.

This doesn't mean we're done - it doesn't have error
propagation and is not enabled by default - but we are
close.

The next patch will finalize and enable testing.

Test-Parameters: trivial
Signed-off-by: Patrick Farrell <pfarrell@whamcloud.com>
Change-Id: I34020357037bdcf400ffe7f3b4dc14ea5e5a23c7
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/57295
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Marc Vef <mvef@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>