Design work for Database Read and Column Types

[jdunkerley]

Pull Request Description

Important Notes

Checklist

Please include the following checklist in your PR:

• [ ] The documentation has been updated if necessary.
• [ ] All code conforms to the Scala, Java, and Rust 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 dist and ./run ide watch.