files/group: add sgx group with static ID for new systemd

files/group: add sgx group with static ID for new systemd

Yocto Project 4.0.9 now comes with systemd v250, which uses sgx group:

https://git.openembedded.org/openembedded-core/commit/?h=kirkstone&id=3fd47697df858d4093d9cb4c6a378fc07aa4d064

Note: here sgx is not related to Imagination PowerVR GPU, but rather
means Intel Software Guard Extensions:

https://en.wikipedia.org/wiki/Software_Guard_Extensions

Bug-AGL: SPEC-4768

Change-Id: I3f8656b5e859f1126388f52d9f8b54bfac0734a7
Signed-off-by: Denys Dmytriyenko <denys@konsulko.com>
Reviewed-on: https://gerrit.automotivelinux.org/gerrit/c/AGL/meta-agl/+/28720
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>
(cherry picked from commit 718394298c12ab1d1a384d940d883c2b60adf8d9)
Reviewed-on: https://gerrit.automotivelinux.org/gerrit/c/AGL/meta-agl/+/28765
Tested-by: Jan-Simon Moeller <jsmoeller@linuxfoundation.org>