Show dependent objects in delete dialog sheet

It would be great if the dialog box would show the dependent objects in the delete dialog.
It should be possible to get the dependance tree from the `pg_depend` sys catalog.
The dialog should only show the cascade option if at least one object depends on the db-object.
It should also display the number of dependent objects and have a toggle switch to list these.

I think such a feature would prevent some unintentional `DROP CASCADES` and would be greatly appreciated.

Start by locating the delete dialog sheet and the database access code that can query PostgreSQL's pg_depend catalog. Trace how dependent objects and cascade deletion are currently handled, then verify that the dialog conditionally shows the cascade option, dependent-object count, and expandable list as described.

Written by the indexing model from the issue text.