Fixes whitespace only comments not being able to be updated

What does this MR do and why?

This fixes a bug where comments left on an unchanged whitespace diff would throw an error when trying to update. This is caused by the position property being sent in the request to update but it does not include the ignore_whitespace_change property.

MR acceptance checklist

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Screenshots or screen recordings

How to set up and validate locally

• Create a comment on a diff when Show whitespace changes on an unchanged line that would exist when the Show whitespace changes is checked
• Refresh the page on the overview tab
• Edit the comment
• Comment should be saved