Improve tables for incompatible subsets

[jfoster17]

Catch IncompatibleAttributeError for subset-only tables and show newly-valid subsets

Description

There were a few state problems with tables and incompatible subsets. This fixes the following two issues:

1. A table without the underlying full data layer visible (i.e. just one or more subsets) would generate an uncaught IncompatibleAttributeError when any of the visible subsets became invalid (i.e. because they were no longer subsets on the tabular dataset.
2. When a subset was disabled for a table viewer (because it was incompatible), later redefining that same subset on the tabular dataset did not re-enable the subset layer in the viewer, which makes it look as if the subset creation did not work.