Avoid overwriting files in page media upload

Hi,
can we make the media upload field to prevent image overwriting, while uploading a file with already present name? I know that it's possible to add own file upload field and set `avoid_overwriting` to `true`, but why it's not by default on page media? Is there any reason why to not do that? I think that would be way more user friendly than overwriting already uploaded files.

Start by tracing the page media upload entry point and compare it with the existing `avoid_overwriting` option for custom upload fields. Confirm the desired behavior for an upload whose filename already exists, then verify that existing files are preserved and new uploads receive distinct names.

Written by the indexing model from the issue text.