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.
Implement new Enso documentation parser; remove old Scala Enso parser.
Performance: Total time parsing documentation is now ~2ms.
# Important Notes
- Doc parsing is now done only in the frontend.
- Some engine tests had never been switched to the new parser. We should investigate tests that don't pass after the switch: #5894.
- The option to run the old searcher has been removed, as it is obsolete and was already broken before this (see #5909).
- Some interfaces used only by the old searcher have been removed.
[Task link](https://www.pivotaltracker.com/story/show/184012434)
This PR implements Intermediate Representation for our documentation. Later these data structures would be used to generate HTML and CSS for the documentation panel. For now, we display it in the debug scene.
https://user-images.githubusercontent.com/6566674/210674850-480a3e6e-76c3-4f34-a235-15c44dc9ec01.mp4
# Important Notes
- `suggestion-database` now lives in a separate crate
- also, two utility crates were introduced for the `notification` and `executor` modules of enso-gui
- documentation debug scene is moved to a separate crate
- All refactorings are done in the last two commits
