* Support "prepare-upgrade" through "krillup" binary.
* Package the new `krillup` binary and man page into a separate DEB/RPM.
* Also switches to building in a Rocky Linux container due to repeated CentOS 8 vault repo timeouts.
* Mention correct config file location on CLI help.
* Remove incorrect reference to non-existent help subcommand for krillup.
* Add locking to upgrade process.
Co-authored-by: Ximon Eighteen <3304436+ximon18@users.noreply.github.com>
Cross compile DEB packages for armhf/ARMv7 and aarch64/ARM64 using the Rust Tools team cargo cross tool.
Tested on Raspbian 11/Debian Bullseye on a Raspberry Pi 4b (armhf) and Armbian/Debian Buster on a Rock64 (aarch64).
Doesn't yet support stripping of cross compiled binaries (revisit this when Cargo supports the Rust 1.58.0 strip feature) or automated determination of DEB dependencies for cross compiled binaries.
Also removes a duplicate `--system` argument to `useradd` in the RPM `postinst` script.
