Warn on bidirectional Unicode text (CVE-2021-42574)

[0xC0ncord]

Feature Description

After the public disclosure of CVE-2021-42574, Github now displays a warning when a file's contents include bidirectional Unicode text in order to mitigate the effects of the flaw.

It would be nice if Gitea could implement similar functionality.

Screenshots

No response

[amber-ailuridae]

This is a big deal for development teams looking to mitigate risk related to CVE-2021-42574. Proper code review is considerably harder without a feature like this in place.

[bagasme]

For the wording of warning message, I suggest:

This file contains hidden Unicode characters that may be processed differently from what appears below.
If your use case is intentional and legitimate, you can safely ignore this warning. Consult documentation
of your favorite text editor for how to open this file using `DOS (CP 437)` encoding instead of Unicode,
to reveal hidden characters.