Copy Styles after insertNewColumnBefore

[oleibman]

Fix #1425 which went stale 5 years ago, and which I've reopened. Style was not being set properly for last row. Also, Style was not being set at all for insertNewColumnBefore('B').

This is:

• a bugfix
• a new feature
• refactoring
• additional unit tests

Checklist:

• Changes are covered by unit tests
  • Changes are covered by existing unit tests
  • New unit tests have been added
• Code style is respected
• Commit message explains why the change is made (see https://github.com/erlang/otp/wiki/Writing-good-commit-messages)
• CHANGELOG.md contains a short summary of the change and a link to the pull request if applicable
• Documentation is updated as necessary

[oleibman]

There's clearly a problem with Scrutinizer. Don't care.