Fix missing visualization preview in CB

[galin-enso]

Pull Request Description

Closes #5639

This PR fixes a regression introduced in #4120, due to which new nodes that were being edited had an empty visualization preview. Now newly created visualization containers do get a default visualization set even before the visualization's input type is set.

unknown_2023.02.24-19.05.mp4

Important Notes

Checklist

Please include the following checklist in your PR:

• The documentation has been updated if necessary.
• All code conforms to the
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  and
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  style guides.
• All code has been tested:
  • Unit tests have been written where possible.
  • If GUI codebase was changed: Enso GUI was tested when built using BOTH
    ./run ide build and ./run ide watch.

[vitvakatu]

@farmaazon
I checked this PR. Preview visualization is visible now, though its behavior is a bit weird.

1. I pressed enter, then edited the node by adding argument – it showed panic expected arg1 to be Function but got Function, which is a bit shizophrenic.
2. I pressed tab and tried typing different arguments. The value in the preview did not change, even after some waiting. Moreover, some values produced the same panic, even though others didn't.

2023-02-27.17-46-22.mp4

This PR is not the cause though, as it happens on develop as well (except it does not show preview on develop).

The reason for such behavior is in our searcher implementation:

We replace the expression with suggestion preview, and sometimes it is left in the code even though the the CB does not have any entries visible. Moreover, the previewed suggestion can be different at different times (perhaps it is caused by different ordering of filtered results when your enter different numbers). Otherwise the preview always shows the default value of index 0, and you can't see a preview of a different index.

[vitvakatu]

QA: accepted, given the said issues are also reproducible on develop.