Description of proposed changes

For modules like surface and grdcut that output an xarray.DataArray grid, we need to ensure that the registration and gtype information is loaded properly into the xarray.DataArray before the temporary netcdf file gets deleted.

Fixes #524

Reminders

• Run make format and make check to make sure the code follows the style guide.
• Add tests for new features or tests that would have caught the bug that you're fixing.
• Add new public functions/methods/classes to doc/api/index.rst.
• Write detailed docstrings for all functions/methods.
• If adding new functionality, add an example to docstrings or tutorials.