configs: Include AppArmor support

AppArmor security has been a long-requested feature. This commit
adds the config settings necessary to allow it to be enabled at boot
time using the kernel command line (cmdline.txt) - just include:

    lsm="apparmor"

The commit also includes a few settings to give better control over
processes or containers.

See: https://github.com/raspberrypi/linux/pull/1698



Signed-off-by: Jean-Christophe Berthon <jcberthon@users.noreply.github.com>
Signed-off-by: Phil Elwell <phil@raspberrypi.com>