Kexi: fix creating new reports - load layouts only for opening, not creating
Original code worked only because results of operations was not checked.
- move layout loading code to loadSchemaObject() - it was not implemented before
- createWindowData() is now trivial
- add checks for failed parsing of layout xml
- don't store report name, this information is in KexiWindow's part item already
Differential Revision: https://phabricator.kde.org/D211