HPCC-8713 - Re-instate xmlsize functionality

Add 'xmlsize' option to daliadmin, that given an xml file
will analyze what branches use what percentages of the whole

Signed-off-by: Jake Smith <jake.smith@lexisnexis.com>
Merge pull request #3913 from jakesmith/xmlsize

HPCC-8713 - Re-instate xmlsize functionality

Reviewed-By: Richard Chapman <rchapman@hpccsystems.com>