Improving Expression Support for In Database

[jdunkerley]

Pull Request Description

• Adjust Excel Workbook write behaviour.
• Support Nothing / Null constants.
• Deduce the type of arithmetic operations and iif.
• Allow Date_Time constants, treating as local timezone.
• Removed the to_column_name and ensure_sane_name code.

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 build and ./run ide watch.

[radeusgd]

Looks good, just a few suggestions.

Btw. does the removal of to_column_name usages mean that this basically solves #5583 or do we still need to verify something? I guess before we close that one we should add a few 'adversarial' examples that verify that the escaping works correctly, but on the implementation level it seems to be mostly complete?