systemd: split systemd-container

systemd: split systemd-container

Split container/vm related units into a new package, systemd-container.

The split mainly references Fedora 24, with a few differences.
Apart from the bash and zsh completion files, the differences include
adding systemd-spawn@.service into the systemd-container package.

[YOCTO #9835]

(From OE-Core rev: 2a4bf6e4c96a8104733add315166210f04c02caf)

Signed-off-by: Chen Qi <Qi.Chen@windriver.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>