This fixes the inline file preview for rendered files (e.g., markdown). [Here, a live issue in v11](https://v11.next.forgejo.org/mahlzahn/test-inline-file-preview/issues/1) and [the same in v7 (with even more bugs)](https://v7.next.forgejo.org/mahlzahn/test-inline-file-preview/issues/1).
It fixes
1. the inline preview for possibly rendered files, when the link is specified with `?display=source`. This happens, e.g., if you are watching a (e.g., markdown) file in source and then want to link some of its lines.
2. the link to the source file inside the inline preview for possible rendered files (currently it links to the rendered version and then the `#L…` cannot point to the correct lines). This is done by always adding `?display=source` to the link.
Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/6572
Reviewed-by: Gusted <gusted@noreply.codeberg.org>
Co-authored-by: Robert Wolff <mahlzahn@posteo.de>
Co-committed-by: Robert Wolff <mahlzahn@posteo.de>
