Fixes issue writing to a dry run Excel File

[jdunkerley]

Pull Request Description

• Adds size to File.
• If file is empty, then create a new Excel file.
• Fixes dry run Excel write issue.

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,
  and
  Rust
  style guides. In case you are using a language not listed above, follow the Rust style guide.
• All code has been tested:
  • Unit tests have been written where possible.
  • If GUI codebase was changed, the GUI was tested when built using ./run ide build.

[radeusgd]

Please add a test for the directory case.

If we decide to remove the or total size of a folder., then either way it would be good to see a 'negative' test for what happens if size is called on a folder.