Show validation error if no file name is specified

What does this MR do and why?

Currently, users can commit changes to a file without specifying a file name which causes the UI to display an undescriptive error.

This improves the experience by showing a validation error if no file name is specified

References

Screenshots or screen recordings

Before	After
Screen_Recording_2025-03-25_at_10.28.36	Screen_Recording_2025-03-25_at_10.19.23

How to set up and validate locally

1. Find or create a project
2. Click the ➕ button dropdown and select New file in the UI
3. Enter content in the new file, but do not give the file a title
4. A validation error should be rendered
5. Enter a file name
6. The validation error should clear

Related to #521340 (closed)