openharmony-linux.conf: Introduce default OpenHarmony Linux distro

Add openharmony-linux base distribution configuration
as a superset of poky.
For now this distro only enables systemd as a default
init manager instead of sysvinit.

Signed-off-by: Zbigniew Bodek <zbigniew.bodek@huawei.com>

meta-ohos-core/conf/distro/openharmony-linux.conf

+require conf/distro/poky.conf
+
+DISTRO = "openharmony-linux"
+DISTRO_NAME = "OpenHarmony Base Linux Distro"
+DISTRO_VERSION = "0.1"
+
+INIT_MANAGER = "systemd"