test: ListObjectsV2 REST capability, initial multi-page testing

tests/util/util_xml.sh

@@ -0,0 +1,22 @@
+#!/usr/bin/env bash
+
+check_xml_element() {
+  if [ $# -lt 3 ]; then
+    log 2 "'check_xml_element' requires data source, expected value, XML tree"
+    return 1
+  fi
+  local xpath='//'
+  for tree_val in "${@:3}"; do
+    xpath+='*[local-name()="'$tree_val'"]/'
+  done
+  xpath+='text()'
+  if ! xml_val=$(xmllint --xpath "$xpath" "$1" 2>&1); then
+    log 2 "error getting XML value matching $xpath: $xml_val"
+    return 1
+  fi
+  if [ "$2" != "$xml_val" ]; then
+    log 2 "XML data mismatch, expected '$2', actual '$xml_val'"
+    return 1
+  fi
+  return 0
+}