Added OpenUSOS app

Required

• [y] The app complies with the inclusion criteria
• [y] The original app author has been notified (and does not oppose the inclusion) I am the author
• [y] All related fdroiddata and RFP issues have been referenced in this merge request
• [y] Builds with fdroid build and all pipelines pass

Strongly Recommended

• [n] The upstream app source code repo contains the app metadata (summary/description/images/changelog/etc) in a Fastlane or Triple-T folder structure It will be added on full release, hopefully in July.
• [n] Releases are tagged I want to update app manually for now, as it is in beta.

Suggested

• [n] External repos are added as git submodules instead of srclibs
• [n] Enable Reproducible Builds
• [n] Multiple apks for native code App is small

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