in an initramfs, then transition to the real root filesystem. Useful
for systems requiring early boot tasks like LUKS unlock, LVM activation,
or network boot before mounting the real root.
Adds INIT_CMD_SWITCH_ROOT API command, `initctl switch-root` subcommand,
and HOOK_SWITCH_ROOT plugin hook point. The implementation gracefully
stops services, moves virtual filesystems (/dev, /proc, /sys, /run) to
the new root, deletes initramfs contents to free memory, then execs the
new init as PID 1.
See GitHub Discussion #292 for background.
Implement Linux capability support for services, allowing them to run
with minimal required privileges instead of running as root. This uses
the modern IAB (Inheritable, Ambient, Bounding) API from libcap.
Aaron Andersen