Pull Request Description

• Fixes Visualizing a Vector that contains a DB_Column crashes the visualization #12244
• I thought that it may make sense to distinguish DB from in-memory columns in visualization so added the DB_ prefix in the visualization.
• For more nested (not shown on screenshot) DB_Column/DB_Table we don't fetch the row count as that is a costly operation.
• For unnested we still fetch (although open to changing that), but do not fetch the items for DB_Column - just display the row count.

Important Notes

Checklist

Please ensure that the following checklist has been satisfied before submitting the PR:

• The documentation has been updated, if necessary.
• Screenshots/screencasts have been attached, if there are any visual changes. For interactive or animated visual changes, a screencast is preferred.
• All code follows the
  Scala,
  Java,
  TypeScript,
  and
  Rust
  style guides. In case you are using a language not listed above, follow the Rust style guide.
• Unit tests have been written where possible.
• If meaningful changes were made to logic or tests affecting Enso Cloud integration in the libraries,
  or the Snowflake database integration, a run of the Extra Tests has been scheduled.
  • If applicable, it is suggested to paste a link to a successful run of the Extra Tests.