Add missing xmlparser attributes: namespace_prefixes, ordered_attributes, specified_attributes, intern by Copilot · Pull Request #6494 · RustPython/RustPython

- Added namespace_prefixes, ordered_attributes, specified_attributes (boolean attributes)
- Added intern dictionary attribute
- Added stub handlers for all missing handler types to ensure compatibility
- Created bool_property macro to ensure boolean attributes are converted correctly

Co-authored-by: youknowone <69878+youknowone@users.noreply.github.com>

- Tests for buffer_text, namespace_prefixes, ordered_attributes, and specified_attributes now pass

Co-authored-by: youknowone <69878+youknowone@users.noreply.github.com>

- Use proper error propagation in bool_property setter instead of unwrap_or
- Add comment explaining the purpose of the intern dictionary attribute

Co-authored-by: youknowone <69878+youknowone@users.noreply.github.com>