When saving, the default file name is "untitled" regardless of
selected language. This can be translated, like many graphical
applications do.
This applies to:
- blend file
- alembic file
- collada file
- obj file
- usd file
- rendered image
- grease pencil export
- subtitles export
- other Python exports through ExportHelper
Reviewed By: mont29
Differential Revision: https://developer.blender.org/D15868