[Feature] state:modified consider external table column name changes as changes

[dat-a-ish]

Describe the feature

Hey, external tables column changes aren't considered as a change when we run:

 dbt ls --select "state:modified"

I believe that this happens because it's a source definition. Is it possible to include column changes to state:modified for external tables?

Additional context

This is very similar to this issue. The difference is that columns' definition for regular sources can't really break downstream models, unlike columns' definition for external tables' columns.

Who will this benefit?

Anyone who wants to run CI tests, build downstream models each time external tables' columns were changed, and catch a wrong reference problem before production run.