This moves the 3.0 specific patches and files to an openharmony-3.0
directory.

Instead of using DISTRO_VERSION, this now uses OHOS_VERSION to determine
which OpenHarmony is built. DISTRO_VERSION has been reset to 1.99.99 to
stick to oniro-core and avoid confusion with OpenHarmony version (3.0 or
3.1 for now).

Signed-off-by: Thierry Escande <thierry.escande@huawei.com>