Grid columns are duplicated when coming back from Import panel

[insmac]

Steps to replicate:

1. Open up Web Console, and execute any query that returns columns (might be 0 rows, just that the columns are rendered).
2. Go to Import
3. Go back to the Grid. The columns are duplicated every time the user goes back to it. The rows are correct.

The columns seem to be generated again when the grid is back into view, via this method:
https://github.com/questdb/ui/blob/main/packages/web-console/src/js/console/grid.js#L1452C41-L1452C41
which is triggered if deferVisualsCompute is set to true (that happens when grid goes back to view).

Running the query again (i.e. clicking "refresh") clears the viewport and fixes the problem.

Screen recording:

CleanShot.2023-11-10.at.12.00.04.mp4

[insmac]

Fixed in #230