Fixes #7468

The fix is pretty simple: we reuse the existing functionality for importing stuff and generating expressions. It fixes issues with `Nothing` or `Report_Unmatched` types.


https://github.com/enso-org/enso/assets/6566674/4e7addf9-2175-4f2a-a571-4ef823de5cb0

While debugging, I found it easier to work with a suggestion database when exported to some external format. Hence, I implemented serde serialization support for database entries and also a new debug shortcut <kbd>ctrl</kbd>+<kbd>shift</kbd>+<kbd>u</kbd> to dump all entries to the console.