Aarch64 support

Fixes #103 (closed)

• edit README for nightly build link
• Test the build on my Xperia 10 it wont install, because 32 bit user space of course.
• Tooling is not available via repos for 3.4.0.22, so it has to be added manually through the kickstarter system. Tracking https://github.com/CODeRUS/docker-sailfishos-platform-sdk/issues/2
• Some compile issues (see below) that need treatment in qmetaobject(-sfos)-rs.
• Enable aarch64 deployment to Openrepos in CI