Draft: Build system app

Description

Build system app with the docker image

Issue(s)

https://gitlab.e.foundation/e/priv/os/build/-/issues/54

https://gitlab.e.foundation/e/os/backlog/-/issues/213

Test environment

Run a build with the APP_NAME env variable

Test procedures

Confirm the build returns an APK, that can be installed on a test device (as by default, signed with test keys)

Technical details

Screenshots

Check list

• Self review
• Test procedure explained
• Tested on fresh install
• Tested applied as an update
• License
• Internal documentation
• User documentation