Add a new group of commands - "posix". The current command categories
are not a good fit for that: "projects" is for CI, "distro" is
distribution-specific for CD, and secrets is for handling secrets
specifically. Introduce the more general command group "posix", a
class of commands not POSIX compliant in the exposed API, but
primarily using POSIX utilities as workhorse.
Signed-off-by: Jan Lindemann <jan@janware.com>