meta-agl-core: add kuksa user and group

meta-agl-core: add kuksa user and group

Add a kuksa user and group to the static passwd and group files to
facilitate running the KUKSA.val Vehicle Information Service (VIS)
server as non-root and control access to some of its configuration
files.

Bug-AGL: SPEC-4405

Signed-off-by: Scott Murray <scott.murray@konsulko.com>
Change-Id: I199d79df42a6e5ea032ccfa084a1d38625b508f0
Reviewed-on: https://gerrit.automotivelinux.org/gerrit/c/AGL/meta-agl/+/27557
Tested-by: Jenkins Job builder account
ci-image-build: Jenkins Job builder account
ci-image-boot-test: Jenkins Job builder account
Reviewed-by: Jan-Simon Moeller <jsmoeller@linuxfoundation.org>