BUG: Add ReadXMLToList to XMLMetadataSupplier

ReadXMLToList from GDAL is not part of the public API. It can be used
when compiling libgdal without --with-hide-internal-symbols
switch. But libgdal from Debian and Ubuntu packages doesn't contains
the symbols. The adopted solution is to implement a ReadXMLToList
function for the OTB.
2 jobs for metadata-sentinel1 in 26 minutes and 1 second (queued for 2 seconds)
Status Job ID Name Coverage
  Precheck
passed #26765
fast-build

00:26:01

 
  External
passed cdash:ubuntu-18.04-fast