Kas

- isar: Take qemu-user-static from buster and adjust binfmt setup

- kas-docker: Restore KAS_PREMIRRORS support

- kas-docker: enable passing SSH configs
- kas-docker: add --no-proxy-from-env option
- kas-docker: Pass in NO_PROXY
- Add KAS_PREMIRRORS support
- Remove SSH_AGENT_PID forwarding

- Recursive include handler refactoring and cleanups
- A lot of code cleanups, refactoring and bug fixings
- Isar docker support improvements

- Add patch support for repos
- Use git diff-index to check if repo is dirty
- docker: add debootstrap and qemu-user-static

- Add iproute and zx-utils to the docker image
- Fix relative path for repos
- Write MACHINE and DISTRO as weak defaults