Fix propfind type of subnodes with depth >= 1

When custom properties are manually added in a plugin with the `propFind` event like in this example: #482 and depth >= 1, the subnodes' propfind's type was incorrectly deducted.
This resulted in custom properties only added to the first node and not on the subnodes.

lib/DAV/Server.php

@@ -895,7 +895,7 @@ private function generatePathNodes(PropFind $propFind, array $yieldFirst = null)
  }
 
  $propertyNames = $propFind->getRequestedProperties();
- $propFindType = !empty($propertyNames) ? PropFind::NORMAL : PropFind::ALLPROPS;
+ $propFindType = !$propFind->isAllProps() ? PropFind::NORMAL : PropFind::ALLPROPS;
 
  foreach ($this->tree->getChildren($path) as $childNode) {
  if ('' !== $path) {