fix: the plugin should not blindly add the fillcolor to "widgetOptions"

The internal "widgetOptions" field, where is stored in particular the conditional formatting (e.g. fill color) when the formula is True, is not properly handled.

This results in inconsistent internal data, that may break a number of functionalities.

This should be fixed before the first release as it is difficult to getting straight after the fact as it involves inaccessible internal data, and I don't want to knowingly mess up a production table.