wip: New App: aTox (ltd.evilcorp.atox)

• The app complies with the inclusion criteria
• The original app author has been notified (and supports the inclusion): if this means the forked app Author
• All related fdroiddata and RFP issues have been referenced in this merge request: no related issues opened
• The upstream app source code repo contains the app metadata (summary/description/images/changelog/etc) in a Fastlane or Triple-T folder structure: with neither apps specifically but has their standard file layout
• Builds with fdroid build
• Releases are tagged