When exporting to Excel, the option to export the "network_weights" sheet should be available at all times

[kdahlquist]

When exporting to Excel, the option to export the "network_weights" sheet should be available at all times. The "network_optimized_weights" sheet should only be available if there is edge weight data, but the "network_weights" sheet should always be available. It should be identical to the "network" sheet.

I apologize if I said differently before.