When saving a file, use unique name if file exists already

### Your use case

#### What would you like to do?
When saving a file and a file already exists with the same name, make the save dialog use a new unique filename.

#### Why would you like to do it?
Currently when saving images for example some file types are always saved as image.xxx which causes a problem when saving more than one. Each subsequent file has to be manually renamed.

#### How would you like to achieve it?
With something as simple as:
if image.png exists the saving dialog will give the new file the name image1.png...

### Have you considered any alternatives?

There are none.

### Additional context

_No response_