Resolve "Re-name files in Web IDE in a more natural way"

What does this MR do?

Resolves https://gitlab.com/gitlab-org/gitlab-ce/issues/58802 by:

• As per Issue: putting just one entry into Change set after clicking "Commit" instead of two

Before	After
re-name-files	re-name-files

In addition This MR fixes:

• code highlighting when re-naming files different from plain text

Before	After
re-name-files-highlighting	re-name-files-highlighting

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation created/updated or follow-up review issue created
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Performance and testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers

Closes #58802 (closed)