Make it work on Android

I tested it with a local Craft build. This MR on its own is good to go, but there are a few more things needed to have a working Android app and CI.

Qt5 CI

1. sysadmin/ci-images!92 (merged) to be able to build mpfr
2. Add mpfr to CI Image (maybe a small adjustment to the blueprint to add texinfo as a build dependency is needed)
3. Add CI

Qt6 CI Not sure what is needed

Make APK work

1. Make KF5Feedback official.
2. Add a Craft blueprint for KF5Feedback
3. Add KF5Feedback as a dependency to the Kalk blueprint
4. Add a build pipeline to Binary Factory (maybe needs more changes somewhere) or wait until we move it to GitLab (hopefully soon)