security.txt file detector per Olivier Debré

The extension aims at helping ethical hackers to check easily and quickly if a website publishes a security.txt file (cf. RFC 9116 A File Format to Aid in Security Vulnerability Disclosure).
It does so by:
- showing a red (no such file) or green icon (file present);
- displaying its content.
Caveat: When a [root directory]/.well-known/security.txt file exists, its content is displayed without any syntax check.

Note to people intending to get in touch with me to “help my extension grow”, “drive growth for Firefox extensions”,...: don't waste your time, I definitely do not want to waste mine. This extension is, and will remain FREE.